Help-What is this hard red bump (enlarged pea size) on my breast (upper inner area-not near nipples, no discharge, sore to touch)right under skin?

Needs to be checked. Any new breast lump, bump or skin changes needs to be examined by your doctor. Usually these findings are benign but they need to be evaluated to be sure especially at your age. If you feel comfortable you could do a virtual visit on healthtap if you think the pea sized area would be visible on video chat or with an attached image.