root canal infection severe pain - help!!

[JewelsM2009]

Had a root canal 2 yrs ago in tooth #29 or 30 ((R, front, fifth from front, lower).  From amalgum to tooth colored filling (had absess (abscess) in past along gum line - usual tooth ache).  2 weeks ago Fri. had pain in tooth, with gray discoloration.  Got in to dentist Mon, he referred to Endo for next day appt. and began Pennicilin 500 mg., t.i.d.  Endo began root canal, anesthetic would not "kick-in", very painful procedure.  He hit great deal of pus under tooth although my gum was not swollen (cheeks and neck were).  He increased Penn to Q.I.D. and decided to se me the following week when infection had a chance to improve stating that was contributing to anesthetic not working.  Upon arriving home fel like tooth leaked hot lava from underneath, took pain meds, atb and slept, awoke with less pain.  Next afternoon - excruciating pain, severe swelling.  Went to ER, received pain block and changed rx to Clyndamiacin 300 q 6 hrs.  Next day pain worse, endo rushed me in, sliced my gum to release pus (even though no absess (abscess) along gum) and got some, but not much, told me to milk it.  Back in ER as swelling worse that eve., temp. 99.9, neck swelling, pain not touched by meds.  Send to oral surg. - suggested seeing endo Monday, xray reflected inf. in bone and adjacent tooth not looking great either.  Finished ATB this Mon., back to Endo, anesthesia to finish root canal didn't even numb lip, he said due to acidity perhaps?  Very painful, jawbone and cheekbone hurt most, tooth throbbing, meds do not touch it!  Could not finish procedure, rx'd another dose of ATB and will follow-up next week for possible extraction or completion.  My Q:  what is going on?  Why isn't anesthetic working?  How will we pull tooth if anesthetic won't work?  When he injected anesthetic today, felt like hot lava again traveling immediately down to base of tooth (shot was not right next to tooth) what is that - nerve damage?  I have had sensitivity in tooth somewhat since previous root canal could I have had a dormant infection since then?  And should bone infection be treated differently than regular infection?  Not sleeping in two weeks and constant pain are almost unbearable - this is crazy.  For someone with a high pain tolerance - I feel like a whimp!!!  PS I have TMJ - does this complicate things?

[scottma]

If you are not immune compromised, the treatment procedure provided by your dentist generally clears up infection in 72 hours. In my opinion, clindamycin + metronidazole may be more effective. As long as your endodontist thoroughly debrided the canal, there is really not much we can do further. It may take a while to get rid of infection. Irrigation with sodium hypochlorite may irritate periapical tissue and causing more pain. Irrigation with normal saline or chlohexidine may be less painful.Going back to your endodontist is advised.