I think it may be a simple fungal infection
, which can be treated with a topical anti fungal cream. however, given your age it is extremely important that you see your doctor for an exam and a biopsy
to make sure it isn't something more serious like a cancer. although your description doesn't sound like it, there are some cancers that can present this way, and the only way to know for sure is to see your doctor as soon as possible. please feel free to let me know if you have any more questions, but please don't delay seeing your doctor.