That's good. Sounds like it was a blood blister from biting.
i only had it for one day. then it's gone after. wew.
May be a blood blister from eating rough, hot and spicy foods, or something hot. Biting yourself accidentally or irritation from a rough tooth.
You do not say how long you have had it and in which part of the mouth it is. If you have had it for over a week and it does not look as if it going away, or it starts to enlarge, then see your doctor or your dentist.
Best wishes.
could this be sexually transmitted?? We make sure that every thing is clean. =_____=