bald patches

I'm wondering what may be causing my coton de tulear's bald patches near her hind legs (both) and on part of her stomach. It looks like she has been shaved, but she hasn't! Originally, she was on the Evo small bites, then she started the Evo 95% red meat, and that is when I noticed the baldness (several months ago). I switched her back to the regular Evo, then I tried switching her to Orijen. The hair never grew back, and the vet said maybe it was a flea allergy, even though she never has any fleas, or chews or scratches that much! I have switched her food again to the Wellness Simple food of Venison, Brown Rice, Brown Rice Protein, Flax Seed Oil, and 1 other ingredient, and after a whole bag of that, the hair still has not grown back!
Should I keep her on this limited ingredient diet, or do you think she should maybe go back to Orijen, or Orijen fish? Is fish hypo allergenic? I think I prefer the Orijen to the Evo; what do you all think?
Since she does not scratch that much, do you think it even is a food allergy; or something else?
What could I do to help her hair grow back?
I appreciate all of your help!

How old is she?

Does she have any other symptoms?

she is 2 1/2 years old, and has no other symptoms

There are a couple of Coton people on another board I frequent and I know one for sure has said that her Cotons don't agree well with grain-free diets like Orijen and EVO. She's had a incredible results with regular Innova.

Not sure if that would help the bald patches or not though.

Actually, I started her on Innova as a puppy, and she did not like it at all; refused to eat it! That is why I switched to Evo. Currently she eats the Wellness Simple Solutions which is 1 protein (venison) and 1 carb (brown rice) and some fat (flaxseed oil, etc.)
What board is it that the Coton owners are on? I would be interested in hearing their problems encountered with this breed!

hey i got those,,,lmao,,,j/k