It sounds like she may have eaten something that didn't agree with her or perhaps didn't eat close enought to her last meal and developed some excess bile leading to nausea. Dogs frequently eat grass when they are feeling nausea. It is unknown if they eat grass to vomit or if the grass makes their stomach feel better. But they seem to vomit frequently after eating grass.
Mucous on the stool indicates inflammation in the intestines. This could be caused by an unusual treat, parasites such as worms, disease or even a protozoan infection like coccidia or giardia. The most common worms found in dogs are: Roundworms, Hookworms, Tapeworms, and Whipworms and Heartworms
In some cases these worms are passed from the mother to the puppy or in dirt, in other cases such as tapeworms, they are contracted by other methods such as ingesting an infected flea. Most over the counter medicine will only kill one or two types of worms, so your best bet is to take a fecal sample to your vet to determine the type of worms your dog may have and then decide on treatment. Dogs should be checked for worms periodically even if they appear healthy. This is so if your pet does become ill, you are not fighting a worm infestation along with a more serious problem.
For additional information about worms, see this site
Common dewormers are Panacur, which is a prescription product so you need to obtain it from your Vet and it works on roundworms and whipworms. Wormers labeled as Pyrantel Pamoate are the best over the counter medication for roundworms. Drontal plus is also a prescription product and is used for the treatment of Tapeworms, though dewormers with praziquantel work well against tapeworms. Revolution and Interceptor as well as other heartworm medications also control whipworms and roundworms. Another reason to keep your dog on Heartworm medication.
Information on coccidia
Symptoms are diarrhea which could be mild or severe depending on how infected they are. If severe there may be blood and mucous along with vomiting, loss of appetite leading to dehydration.
Information on giardia
Symptoms of giardia are diarrhea with possible terrible smell, mucousy stool and sometimes bouts of vomiting.
Other causes could be anal growths, infected anal glands and inflammation within the large intestine. You can read about the various cause of red blood in the stool here:
For right now, I would put a drop of pancake syrup on her tongue to keep her glucose level up and prevent hypoglycemia (low blood sugar). I would then try feeding her small portions of boiled chicken and rice to give her stomach a break. If she does well, you can gradually add back in the kibble and vegetables. If she still is having problems, then you will need to have her seen.
The following symptoms should trigger an automatic trip to the vet:
If your dog has acute vomiting and diarrhea lasting over 24 hours.
If your dog becomes dehydrated. You can tell by pulling up the skin between your dog's shoulder blades and seeing if it flows back down normally. If it stays tented or is slow to return to normal, your dog is dehydrated and needs fluids immediately and should see a vet as soon as possible.
If your dog's gums and tongue become pale and not their normal pink color.
If your dog's rectal temperature is over 103F (101-102.5F is normal)
If your dog becomes lethargic and non-responsive.
If your dog has trouble breathing.
I hope you find this information helpful.