Guinea pig has dry spots?

I got a guinea pig from a petsmart about 3 days ago. When we bought her I noticed she had two cowlicks on her back. Her skin was perfectly fine. Her feet were kinda peeling/dry. Well I noticed today her Cowlick spots are dry and flakey.. Slightly red. No other spots on her body are besides her feet still. I am worried its something serious. We cage was clean when he arrived, top to bottom. We had a guinea pig for about a week before we got her.. She caught a cold.. We brought her back and she was treated and now she is healthy(we just purchased her back). Well now I am scared she may catch it if it's something serious? They really enjoy each others company so far. Just worried.