IF it's the PT, you might be overdoing it just a bit..once that 'heavy' feeling starts creeping in...speak up and STOP! As for the pain clinic itself, what are you doing there that's triggering things?
If you read some old posts, you'll find that lots of good, bad reactions can happen, as well as no reaction at all.
The top 'sticky' includes a post listing a large number of medications that could be tried. I truly hope there's one there for you.
I know you've been reading hard and asking lots of very relevant questions. It's a lot to take in while you hurt like the 'Dickens'! Hang in there - j