I think I've had TOS for about 10 years but only the last 3 have been unbearable. I had a horse fall on me 4 yrs ago exacerbating the problem.
I work for vascular surgeons and had been asking them for years if it could be TOS and they always said no, it was just Raynauds. That was until 8 months ago, I couldn't take the pain anymore and I asked our ultrasound tech to run a study just to ease my own mind and she freaked out at the results and went right to my bosses. (it was normal laying flat but when sitting up the subclavian artery occluded) They were so sorry for not believing me all these years!!! And I highly respect and regard my bosses, they are the best in their field but like alot of docs always checked my pulse with my arm in the wrong position. Thus not occluding the artery. But once I had ultrasound proof it was easy to replicate it. Now they bug me weekly as to when I'm having surgery!!!
My pain is about a 4 most days but when it's bad there are no words to explain it.
So I guess it depends on the individual has to how long you can endure the pain and getting the right diagnosis. For me it was years and alot of convincing.