4 year old-lab and mix breed

Question
She has a large area on her back that keeps getting sores and lose of hair.  I have had her to two vets.  One said is was a fungus - treatment didn't work.  Thyroid problems have been ruled out.  The other vet said she had allergies for me not to give her any beef or items containing wheat flour.  I have done this.  She was given a steriod shot and that helped.  She was put on predizone and that worked until she took all of the medication.  The vet said the cooler weather should take care of it, but it hasn't.  Do you have any idea what, if anything, I can give her or apply on her that might take care of this problem?  Do you know what the problem may be? I would really appreciate your help.  I have tried a little bit of everything to help her.  Thank you.

Answer
If the cortisone helped, then it is probably an allergic reaction to something.  I doubt that the food allergy is a problem, since that rearely responds to steroid therapy. There may also be a secondary infection with bacteria or yeasts.  If she is OK on steroids, you can use them until the weather changes and the allergens are gone.  If there is an indoor allergy, then this may be a non-seasonal allergy, which means she may need something for itching at a low dose all year long.  You can also add something called Omega3 fatty acids to her food, which will help to reduce her skin sensitivity.