It is tough to diagnose and everyone is different. My arm was purple and swollen with a deep itching in my chest, tingling pain in arm shoulder back neck, etc. all of my tests were normal. I was even given a diagnosis of mastitis, never mind the purple arm haha. I had MRI s, ultrasounds, horrible nerve tests, blood tests, etc. Neuro exam all NORMAL! the very last test, a venogram showed 75% mechanical occlusion of my subclavian vein. Find a doc that will stopatnothing to help you. Although rare, they are out there. Oh yeah make sure they do "dynamic"scans very important. Mine were always done with my arm down at my side, no good.