My 13 year old son has a red bubble on his back he said it has popped twice and it looks like a blood blister bit it just fills back up is it a mole or cancer?

Without viewing it I can't answer whether this is cancer or a mole. You should start with your family doctor and possibly get a referral to a dermatologist.

I called today and they said they were going to refer him to a dermatologist but they haven't called me back with an appointment yet