extreme pain

So every time I see my dentist to get a filling, I can only stand it for about a half hour.  Then my jaw locks and the muscles spasm and I get shooting pains up to my temples.  It one of the worst pain I have ever felt.  My head feels like it's going to explode.  He gave me a root canal.  Half way through, I was throwing up and crying uncontrollably do to the pain.  He eventually just stopped and I had to come back another day to finish it.  They have given me pain medication, ibprofen, muscle relaxers, nitrous oxide, you name it.  I did have TMJ, which they fitted me with an excellent mouth guard, but it doesn't help the pain.  My mouth guard no longer fits due to surgery from a failed dental implant (that's $700 down the drain).  So what could this be?  I don't even want to go to the dentist anymore.  It's too painful.

[Jerome Tsang, DDS]

You may want to ask your dentist or friends for a referral to another dentist who may be able to address your TMJ problem.  Sometimes with referred pain or muscle spasms, it can be treated with a cold spray along the muscles which relieves the tension.  I have not tried it myself but have seen lectures on the subject.  It may be worth a try to find a dentist who does it.  Perhaps contacting your local dental society may provide some leads.  Hope that helps.