Hi Eileen,
Was back at the dentist the other day, thinking this might be the final treatment, but alas no.

I was redrilled and another temporary put in place. The problem seems to be that he can't drill as deep as he'd like to, as the bottom is calcified, and he thinks the root end might be going to the side. There might be some infection down there (well, it feels like it to me!), but he found no pus. See him again in a month.
Cheers!
Tizz