Sometimes after TOS surgery you may still need to be on some sort of pain med long term.
The surgeon should have shared that possibility with you, but doing 6-7 of these per year isn't very many.

I'm sure others that had surgery will chime in and share their knowledge first hand.

I think some are on muscle relaxants of some sort to keep things from tightening up.

Don't suffer /tense up with the pain, you do need to keep the pain & tensing at bay.