When I bring my shoulders back I feel a *painful* stretch in the armpit.
I thought I was stretching one of the muscles, but if I reach there, I feel the bundle of nerves tightening, not the muscle.
Same thing happens if I try to do a doorframe stretch (which leaves me with numb fingers).
If I stretch a bit more, the pain radiates up to the top of my scapula.

Asked my wife to do the same and she has a stretch in the bicep muscle as I would expect.
Is this a pec minor syndrome or a TOS symptom?