Pain in tooth while brushing, pressing.

I had root canal on tooth 46 an year ago as it hurts for tapping and biting pressure on it. Sent me to Endodontist. Had root canal for the same reason. No changes. This pain started 1.5 years ago. Had cbct scan before and after root canal. Nothing found evident. I went to new Endodontist now and he said there is some dead space at the End of one root. And wanted to retreat this. Had retreat root canal last week and he placed medicine inside. I felt pain during the procedure when he digged near the root tip. I was numbed though. He said I felt pain at the end of the root. What could be the reason for this pain during root canal retreat? It's been 6 days after root retreat and it still hurts the same as before. Hurts for any little pressure on it. Tooth hurts if I brush on it. all sides hurts.tonguebaide, cheek side and chewing surface.all sides hurts while brushing. I use soft bristle brush.It hurts if I place the tongue on it or push through it. Is this normal to hurt after retreat