Hi Bryanna
Many thanks for your concern and help - it's much appreciated.

My dentist has always been careful to keep me in the picture about what is happening in my mouth, so I was aware of residual bacteria in root canal fillings.

The x-ray was taken when the symptoms first appeared and before I took any antibiotics. It showed no infection, and no cyst, at the base of the tooth (I used to work in radiography department - I could see there was no shadow when shown the x-ray).

It was diagnosed as a gingival abscess.

It was my own dentist who treated me.

He was concerned not to disturb the nerve (the bit which showed up as a tiny white blob near the root and which I don't remember the technical term for, but it deals with sensation to the lip) when extracting so did no additional exploration after taking the tooth and fragments out. He put in a gauze pad.

There was no cyst as far as I know. Certainly didn't show up on the x-ray.

A major concern for me is the length of time this is taking to 'heal', especially given I am not taking antibiotics because of my allergic reactions to two of them. I'm not sure how well my body can fight off the infection without some pharma assistance.

I think, given the issues you have raised for me, that I will ring the dentist today for a telephone consultation to check these issues out.

Many thanks. You have been really helpful in identifying issues for me!
It's much appreciated.