Welcome to Just Answers. I am here to help you out.
There could be several reason for this to occur -- I will list them by frequency seen and then give a full description of treatmetn regarding the first one. I will also attach a link or two at the bottom for you to read and learn about these.
1) Feline atopy or allergic dermatitis -- see below
2) Skin infection with bacteria, fungus, or parasites -- require a diagnosis or trail of various treatments.
3) auto immune disease
4) combination of the above
I'll start with allergies from the beginning.
These can start at any time -- having not reacted like this in the past means nothing.
Allergies are an overreaction of the immune system to specific proteins (called allergens). These allergens could be a protein in a food ingredient, environmental protein (pollen, mold, dust mite, dander, cleaning product, carpet cleaner, etc), or flea saliva (even one bite can trigger this reaction like a person allergic to bee stings).
Most common causes of allergies --
1)Flea saliva allergy is much like a bee sting allergy -- it only takes one bite and it sets off the entire allergic reaction.
3)Environmental things -- pollens, dust, dust mites, molds
The first step would be to trial corticosteroids for a few days. If it begins healing and itch goes away -- then this might be the problem! I would also put #6 below as a first thing to do also -- Very good flea control is essential to helping this or ruling it out. Killing the fleas on the cat after they have bitten will do no good.
It looks as though the home remedies are not working too well -- these work in an infestation of fleas (MANY) or a skin infection from bacteria alone. They never work with allergies --- but once allergies are under control, there may be some natural alternatives to try.
Here is a run down of how this should be handled to get the best results. There are some choices to make in how much you spend, how effective it is, and how bad the side effects are---- First note - there is no cheap and easy remedy that helps --particularly if cortisone shots are short lived in their effect.
To start with -- (remember in your case go to #5 and 6)
1) Allergy testing will use a blood sample to give you a list of the most common allergens in your area and how your dog reacts to each one. This is very helpful -- for example -- you may be on a hypoallergenic food with lamb in it -- if your dog happens to be allergic to this ingredient -- then this is a waste. It comes with a list of prepared foods that would be suitable for your dog. It also allows for hyposensitization shots.
2) Hyposensitization is often a choice if the highest rated allergens are in the environmental category. This is the same as people who receive allergy shots. If you have clear recommendations in the allergy test -- this can result in a 70-90% reduction in symptoms.
3) Antihistamines -- may not be out of the question. I have had terrible results with benedryl. I have had good results in many dogs with hydroxyzine. SOme dogs will do well on loratidine (claritin). These can be used to reduce the symptoms without the side effects of steroids or cyclosporin. Or may reduce the amount of these medications needed -- so that they are more safe. If you haven't tried these -- it is worth a try. They are fairly inexpensive and have low side effects. Usually take 2-3 weeks to get full effect.
4)Diet -- IF you know what ingredients your dog is allergic to -- there are diets out there to feed -- some are expensive, some are not. Or you may chose to make the food at home....but you first have to figure out what ingredients he is allergic to.
5) Steroids -- in small doses can be used sporadically -- but should not be used long term due to side effects. They can effectively be used to help diagnose an allergy (not tell what is triggering the allergy -- you need testing for that). If the skin problem responds to steroids -- then it is likely allergies. Then you can begin finding out what the cause is.
6) Flea control -- make sure you have a good solid product on board at all time -- I use Frontline -- but their are others as well.
7) Last but not least -- think through any cleaning detergents, carpet sprays, bedding materials that your dog may be allergic to. I have seen dogs allergic to each ingredient you listed in your home food.
8)Cyclosporin -- (Atopica) -- this is an older medication with a new use. It is a potent immune suppressant and does wonders for allergies that do not respond well to other things. It does have side effects -- but better than steroids. It's price is worth it in many cases.
This is a little more info than you may have wanted about the topic. As mentioned the first step is to address flea control and attempt to a diagnosis.
Milliary dermatitis -- caused by allergies
Feline allergies and itching
I hope this information helps!_____________________________________________________________________Please click "ACCEPT" if the information I have provided has been of help so I receive credit for my work. Bonuses are always welcome and appreciated. Thank you.The above is given for information only. Although I am a licensed veterinarian, I cannot legally prescribe medicines or diagnose your pet's condition without performing a physical exam. If you have concerns about your pet I would highly advise contacting your regular veterinarian