Suggest Remedy For Discolored, Painful, Sore Skin On Neck

I have a small mole on my neck and this weekend I was wearing alot of necklaces/beads during a party and throughout the night I kept pulling on them to put them back in place because I was moving around alot. Anyway, I noticed that my neck was sore and so I looked in the mirror and now sorta pulled off on one side....not even half way but enough to hurt and it's also changed colors, before it was light brown and small, now it seems bigger and it's really dark, almost like it's filled with blood. anytime my shirt or anything rubs across it, it really really hurts....... should I leave it alone? Should I pull it off? i