Dear friend, welcome to HCM.
I am a bit concerned here,as your sypmtoms may point to a serious disease.
it looks like a thrombosis (clotting)of major vein of the arm/ thorax (chest), where your description fits
do you have fever
, swelling over face, neck?
is breathing heavy?
you need to go to ER and get evaluated for possible major venous thrombosis
. act fast.
till then, you can take simple household pain killers like acetaminophen
act on your doctors ' advice. if they suspect the same as I do, you will need doppler, echo, a CT scan
may be !
take care and keep me informed on your progress.
Good luck !