sore nipples

So I started going to the gym and I guess my bra was too tight or something but my nipples started hurting. Now that I might start my period in like 3 days they hurt even more. :( i don't know what to do to relieve the pain. :(  so it's just my nipples not my breasts. Today I wore my regular bra and it was hurting a lot too, it felt too uncomfortable.