Miliary dermatitis

My cat was diagnosed with miliary dermatitis 2 years ago

her symptoms include

skin lesions
scab formations all over her body
loss of hair
diarrhea

the vet has been giving her prednisone for over a year

she is not getting any better and I have thousands of $$ invested in her care.

do you have any experience with this disease and do you know of anything I could be doing to help my poor cat

Oh, that looks painful, uncomfortable.  I don't have any experience with this--I had to google it to find out what it is--but I note that there are several causes of miliary dermatitis, chief of which is flea allergy.  Assuming that has been addressed, I always think of an allergy to some type of food or additive.  What are you feeding her?

she was on cheap walmart food, I'm trying to get her to eat blue buffalo

As Ritz mentioned, the most common cause of miliary dermatitis is flea bite hypersensitivity. If this has been ruled out/treated, there are other possibilities such as mites, fungal or bacterial infections. However, given the diarrhea, and that other treatments like prednisone haven't worked, I think this is most likely a food allergy especially given the diet she has been on. Dry foods contain many species-inappropriate ingredients, many of which have been known to cause allergenic responses in cats. Grains, fish, and starches are all common allergens.

I would try a novel protein limited ingredient wet food diet. Basically, you want to eliminate any ingredient that could be causing the problem. Allergies develop over time so you want to feed something that she hasn't had before like venison, duck, quail or lamb. For some additional reading, www.catinfo.org has some great feline nutrition and related health issues info written by a vet.