I'm sorry if you do not like my answer. My goal is to provide complete and accurate information. It was unclear what exactly you needed to know based on your description before. If you would prefer a refund I can certainly send this to my moderator.
I am not sure that I can tell you exactly what to expect. Based on what you have written I am worried there is a larger problem going on such as kidney issues, liver problems, chronic pancreatitis or ingestion of something to lead to constipation. Constipation (the hard desiccated stools) is not usually a primary problem, although it can be in rare cases. This usually occurs secondary to an underlying problem that is causing dehydration. I am not sure if the urinary issues are related to a urinary tract problem as I mentioned above or if this is related to straining to pass stool. This makes it very tough for me to give you an at-home remedy. The starting point is for her vet to examine her. Then based on that exam should be able to tell she is constipated, and then lab work will hopefully give us some hints on the why she is constipated. If she is terribly constipated she may need an enema and even IV fluid (or subcutaneous) fluid therapy from her vet to rehydrate her. This decision maybe be based on the level of hydration as based on lab work and her exam findings.
At home you can try to increase her water intake. Offer canned food (slightly watered down). Use broth on her kibble if she is a kibble only cat or give her broth. You can actually syringe an electrolyte solution into her such as Pedialyte (non flavored). For the constipaton, some cats do better with fiber and some do not. You could try adding canned pumpkin to her food. Since she is not nauseated (and is eating well...I thought she was not) then she probably will like the pumpkin. In some cats this really helps. If she truly is not eating then you may safely administer pepcid ac (famotidine) at 5mg (one half of a 10mg tab) once daily; no side effects and found at any people pharmacy.
For the litter box issues, this is complicated. First, she really needs that evaluation to know if there is a medical problem. If not, then you can work on this behaviorally at home. This can be a very frustrating problem! I cannot sugarcoat this for you. This can be very tough to combat. This is why if there is a medical problem, we treat that first and often that resolves the issue. If it doesn't, then, we work on getting her back into the box, but if you want to skip the evaluation and try doing some at-home things then here are some hints.
First, we must assess the litterbox situation. Do you have enough litterboxes? The recommendation by specialists at this point is that you have one box per cat plus one. If you have one cat, you should have two boxes. With six cats, that means seven boxes -- yes it sounds extreme, but this is just the recommendation out there by veterinary behaviorists and internal medicine specialists. Some cats are extremely territorial about their box and may prevent another cat in the household from using the box. An especially fearful cat may not approach a box because something terrifying is between her and the box, such as a vacuum cleaner. Therefore, she will eliminate outside the box instead of approaching it. With two boxes, the problem is solved.
Where is the litterbox located? Cats don’t like to have their litterbox close to their food or bedding. They like to have a consistent, private place to do their business. So, don’t put the box in one of the busiest rooms in the house. Be careful with boxes in the bathroom. If a cat gets sprayed by the shower while eliminating in the box, you can be guaranteed he may refuse to use the box again. Is the box easy for the cat to get into? This may be silly, but some people keep the boxes in a closet and then forget to leave the door open!
I always like to assume you are doing a great job with cleaning the box (scooping all daily; cleansing out the litter entirely every 3 to 4 weeks and when you do this complete change-out you actually cleanse the box itself with a non-ammonia cleaner). I recommend try a different litter. Try one that isn't as dusty and doesn't have an overt odorizer. For example you can try either "World's Best Cat Litter" or "CatAttract". I've had a few clients with success with either one of these.
I think I forgot to mention above that if you have a hood on the box, take it off at least for now. Some cats start to hate the gas chamber effect they create. Other cats that are arthritis or on the larger side have a super tough time maneuvering into/out of the box to go, and ultimately give up and go near it. If you feel like it is a smaller box and one of the offending cats does have arthritis, then perhaps try a larger box that he can maneuver around in. Some people buy one of the tupperware containers that is a low rectangular box and cut an entry-way into it. This works superbly. Our goal is that we want her to love her boxes. We want her to jump in there, scratch around and make a big mess which means they likes being in the box.
Some cats need to be confined to a smaller area for a while until they earn the privilege to get back into the whole house by proving they can consistently use the box. You should not feel guilty about confining her to 1 or 2 rooms for a few weeks until she proves that she is able to do this. During that time you can make the litterbox an excellent experience as noted above.
As some final notes, be sure not to punish her when you find the disasters. I know it is our first instinct, but this only serves to increase anxiety and can worsen the situation.
The other thing it is very important to thoroughly cleanse all areas that a cat has inappropriately eliminated. I recommend using an enzymatic cleaner such as UrineAway or UrineEase. These can help get rid of the odor. If you have carpets, steam clean. If the cat smells it, then (s)he is more likely to go again in these areas...plus it improves the odor for your nose as well.
Cleaners that work:
URINE OFF - there is a formula for dogs and one for cats
Odor removers (to use after cleaning):
Elimin Odor Feline
Cat-Off Odor Concentrate
The list isn't long but that's it. They work. You will read many online that use some of the natural easily available products like Nature's Best, ***** ***** this product like many is very sensitive to temperature and can be affected by other cleaners that you use. So, I can't recommend it.
Please let me know what further questions you have.