### instruction:
If you are a doctor, please answer the medical questions based on the patient's description.

### input:
I have a reoccurring blister that appears behind my last molar in my mouth. It fills with fluid and pops. It reoccurs about every 3 to 4 weeks since I had a root canal on the molar two years ago. I also have a sore throat , sore neck and jaw pain. Please help find an answer for me. My dentist had no idea what is going on.

### output:

Hello, It seems that the root canal treatment you have had about two years ago is left incomplete by the dentist, or you have got recurrent infection in that. If your dentist had taken an x-ray of the area, diagnosis could be confirmed. The molar teeth of lower jaw usually have two roots and three canals. Even if half or one canal is left untreated, the bacterial load increases in that area and re-current infection may occur. Due to the infection, the area fills with pus. The pus gets no outlet to Chat Doctor.  Jaw pain is due to this infection only. Now, to treat this infection, you should visit a root canal specialist (Endodontist) and go for re-root canal treatment. In case, the tooth will have poor prognosis after treatment, the Endodontist will advise you to go for extraction of the specific molar and replacement of the tooth by artificial means. However, the sore throat and sore neck are not related to tooth infection. You might have tonsillitis which is just a co-incidence. You can take Azithromycin (AEE) 500 mg once a day for 3 days and the infection of throat will resolve. Do warm salt water gargles for faster relief. I hope this information helps. Thank you for choosing Chat Doctor. Let us know if we can be of any further help to you. Best,