pain and pressure after root canalg

I had a crown put on no. 19 upper tooth last August. It was always cold sensitive.  7 mo. later my whole mouth , teeth, and head became so painful that I went to hospital for a facial xray, as the pain went up into my temple and side of head so bad I thought I was having a stroke. Nothing showed up.  I went to endonist , he did a root canal and put a temp. filling in.  It has been two month now and I still can't eat or chew on that side.  Temp filling is still in because my dentist said he didn't want to fill it if I was still having trouble.  Now they found a fracture in the tooth under it next to last in mouth.  My bite changes daily...first the back teeth strike each other then changes to front teeth hitting, even when speaking.  They have tried to grind teeth down three times.  I won't have any teeth left if they keep grinding.  Question....why are the teeth shifting every day.  Could the original crown have been too big or not set properly causing all these problems.  The endodonist says he got all the roots.  Could the tempory filling be going bad now causing all of this...HELP.  I also tasted a metal taste for a couple of days burning my tounge.

[Jerome Tsang, DDS]

The teeth shouldn't be shifting everyday.  

I'm not sure whats going on with your situation.  I would recommend having the dentist try a new crown on.  If not, there may be a crack in the tooth, which a root canal won't fix.