What Causes Itchy Nipples With Redness And Irritation?

I am a 27 year old woman with a right nipple which is very itchy. It has been intermittent over the past 2-3 months and seems to worsen when I workout. OTC cortisone cream helps. The top fifty percent of the nipple looks redder and more irritated than the other side. No crusting or discharge. No flaking. Areola is normal and no palpable lumps. No family history of breast cancer. Not pregnant and never had children. The left nipple has itched in the past but is resolved. Concerned about Paget's.