I Have A Loose Tooth With Blister Underneath. Two Months

I have a loose tooth with blister underneath. Two months ago I went in with severe pain shooting up through my jaw and ear. They weren't sure what was causing it. The next week I realized my back tooth on that side was loose. I went to dentist they took x ray said they could see nothing wrong. Now it's very sore, loose and huge blister under that extends up to jawline.