I'm 17 and me and my boyfriend was messing around over the weekend (no sex) and today my right nipple was black/purple. my shirt got caught on it earlier and it ripped off the scab..  Please let me know if i should be worried, first time its ever happened,and I'm sorta scared . Parents aren't involved in my boyfriend and my business and i don't want to tell her about it unless i have to get it checked out. what does this scab mean?

i'm female,17