Oh my gosh, @Mimsy68 - you've been thru the mill & back!! I am surprised they did the root canal during your active treatment, to be honest, as the chance of infection would be increased, I reckon! :(
Coming from a family of dentists (father, brother, uncle, grandfather, godfather .....) I STILL HATE GOING TO THE DENTIST! I used to cry when my dad gave me injections - and go rigid when being given one, even now (as I can't stand NOT having my gum numbed for drilling!) ..... I've always had the worst teeth in my whole family (I think it goes back to me being born 3 months premmie - the tooth lining may not have been developed enough?) So I've always had a mouth full of fillings. :(
However - I would suggest you definitely see your dentist (or at least your GP) - as you could well have an infection in the root canal & be in serious need of antibiotics. :(