What Could Cause Rash On Right Nipple?

for about a year i have had a rash on my right nipple. i kept going back to the doctors and i was on anti biotics as they thought it was a skin infection i was on these for about 3 months and if anything the rash got worse. i then got transfered to the breast clinic and went there a coulple of weeks ago they thought it could be pagets disease but as i am 18 said i was way to young. the doctor said they could either do a biopsy or transfer me to a skin specialist. they are just not giving me any answer and i am starting to get worried as they put the word cancer in to my head. ????