I have very itchy breast with sore painful at times nipples. i had a itchy spot under my breast for a while. it was not infected until after prednison?

See a doctor: this may be something simple like a simple rash or something serious like Paget's disease of the nipple which is associated with cancer. The prednisone knocks down your immune system, so an infection can occur, but the purpose of the prednisone may have been to treat the itchy rash. You may need a biopsy of the nipple to evaluate for Paget's disease. See your doctor