Nip probs

So I just got out if the shower and I was drying off and in some point in time I looked in the mirror.. On right right breast, the outer edge of my nip is darker than the rest of it all the way around. On my left breast it's like that only half way around. The nips themselves have been kinda itchy but the sides of my boobs and under them hurt. I wear a bra only when I'm out I'm public, any other time I'm in a sports bra. Any ideas what's going on?