I have same problem. Before I had silver filling. Dentist said it needs to be replaced. I went with composite resin filling. Before filling, she injected local anesthetic. I felt sharp pain deep inside the tooth (almost at the bottom of the jaw). I told her so. She just rubbed little bit and said it will take little bit time for it to become effective. After that filling is done. Since then I have pain deep inside that tooth. First 2 weeks, it was only for hot/cold and pressure bites. Weeks 3 and 4, it progressed and painful even without touching. I started eating soft food and reduced to only soups. Pain did not go away. I went back to the dentist. She took X-Ray and did not find any problem with tooth. She said no signs of infection also. She just took out the composite filling and put a sedative medicine with a temporary filling. If that fixes problem, she said she will redo filling in few weeks. If it does not, she said a root canal would be needed. If the sedative medicine does not help, she asked me to take pain killers (Advil, Tylenol, etc.) for few days. I am taking Advil, but soon after it wears out, pain comes back. I am suspecting that during the procedure, some nerves were damaged and causing the pain. 4+ weeks is enough time to reduce any temporary inflammation and make it worse if infected. Nerve damage does not show in X-Rays and may not be repairable. If this pain persists, I may bite the bullet and get a root canal (from a different doctor). Glad to know I am not unique, but sad that others are also suffering like this. I paid for composite filling and again to take it out and left with persistent pain. I don't know how much more it is going to cost me (insurance pays for silver filling once a year, problem diagnosis and repairing is not their problem, second filling is on me).

yea, my dentist suggested that I get a root canal too. I was like, you aren't doing anything beyond a cleaning for me now.

It sucks that there may be possible nerve damage as a result.

FYI to those who have had a filling placed, removed, placed again and still experience pain ...

MOST of the time the pain is due to a cracked or fractured tooth which cannot always been seen on an x-ray. The only long term solution to that problem is to have the tooth removed. Root canal therapy will not cure this and only causes more inflammation and new infection to develop inside of the tiny canals that cannot be cleaned out during the procedure.

Hope this information is helpful..
Bryanna