Andreas, welcome to this board!

I don't know if you've noticed but there is a forum for thoracic outlet syndrome here. You might find helpful information there:

https://www.neurotalk.org/thoracic-outlet-syndrome/

I can't advise you on chiropractors as I've never been to one. I use mainstream medical doctors. I'd consider a massage therapist--and have often been to physical therapists, who have been very helpful.

I've known some people who think of their chiropractors as their primary care providers but I just haven't gone that route.