How Can Blotches On The Knees Be Treated?

last evening we noticed 2 circular blotches on the inside of my daughter's knees...one on the right and one on the left, in the same location. At first we thought that it was just a red mark from kneeling or sitting criss crossed but not so. she complained of it hurting and burning on the inside, under her skin. This morning it was still there, and still the same symptoms. she is still complaining of it tingling inside and some pain and it is still red with hard blotches now. any ideas on what to do ? I did put a cortizone cream on it.