My right breast is sore and the nipple is firmer than normal. it hurts a little to wear a bra

Hi Anonymous,
Thanks for your post, and for finding EmpowHER. Breast pain could be a number of things. Have you called your doctor to ask them what they think? It is not uncommon for women to have breast pain associated with hormone fluctuations and menstruation--but I think it's odd you say it's on one side. Let us know what the doctor says.
Here is an article about breast pain and how to alleviate it, hope it helps!
https://www.empowher.com/breast-pain/content/how-alleviate-breast-pain
Good luck, and let us know how you're doing.