Cat with what I think is dry skin?

Question
My cat is about 2 and half years old. I just moved so she was an outside cat now she is inside. We have lived here about a month and the last 2 weeks she has been bitting and scratching her skin open. She has one scab on her head one on her back and several starting from the mid back the whole way to her hips. This all started about the same time she went in heat for the first or second time.(when she was about 3 months old she climbed inside my dads truck motor and she was hit by the fan some how she lived she was very small at that time and the fan kind kicked her out of the motor but still hurt her) Her hair is now starting to fall out on her back. I have put "equate-triple antibiotic ointment" on her twice a day for the past 2 days. I know its not going to fix things right away but im not sure what to do with her. Money is kind of a problem and when I did call the vet they didn't seem to worried about and didn't tell me what to do either. She doesn't seem like it hurts her, she doesn't fight or bite me when I put the ointment on.
I was wondering if it could be the food also. She went from eating cheap Dollar General food my parents bought for all the cats, to now eating food made by "Dads"

I'm also very worried it could be Rippling Skin Disorder. I fond that info on http://cats.about.com/od/healthfaqs/f/ripplingskin.htm
but I think im over thinking. If you can help at all that would be great thanks!

Answer
Hi Stephannie!
Are you sure she doesn't have fleas? What you are describing sounds like a flea allergy.  For cats that are allergic, one flea will do exactly what you are saying. I would make positively sure she has NO fleas at all.  If not fleas, it could be another allergy. I would check into allergies if I were you.

God Bless,
Becky