You have received great advice on this page, Pennypat. I'm not clear though on when you had the root-canals done, it sounds like it was after you got the pain?
The Lyrica is drying out your mouth/throat, which is a common-effect. Keep a bottle of filtered water by you and maybe some hard candy to suck to make your mouth more comfortable. That may also affect the taste in your mouth. You can divide the total daily dose of each drug and take it 3 or 4 times a day instead of twice) if that helps with any side-effects.
Also, you can take some extra paracetamol with the Ultram, I find it especially helps with the dull pain. Don't take any more than 1,000 mg in each dose and remember to factor in the paracetamol already in the Ultram; I think it's 325 mg in each tablet? Check the box to be sure.
You seem to be doing everything you can: keep on trucking, gal.
Cailinruaidh (red-haired girl in gaelic)