I have a big blister in my mouth that deflates and reinflates and hurts. popping doesn't work. i'm kinda worried?

Salivary gland: A mucocele or mucus retention cyst is a minor salivary gland that becomes occluded and can look like a large fluid filled blister in the mouth. A mucocele inside the lower lip will often act the way you have described unless the affected gland(s) are removed.. You should be evaluated by your dentist to confirm if the blister is a mucocele, and if so, have a the affected gland(s) removed.