I have a canker sore on my gum line in the back of my mouth and while brushing it bled and appeared to "pop" (pain is less now). should i be worried?

See dentist: To make sure there is not an abscess in a tooth or a gum infection.

Probably not: At your age, if it continues to improve and then goes away entirely, i wouldn't really worry. If, however, there is ongoing pain after a week, or there are recurrent such sores, you can get checked out. Of note, canker sores don't "pop" so it sounds more like a "bulla", which is different. Good luck.