I was told when I had those type of symptoms that it was a "vasospasm" due to the nerve irritation. Arranging your position so there is less pull on the nerves (i.e. support your arms, good positioning), frequent changes of position, hot water immersions, very gradually working on stretching out the area and very gradually increasing your aoerobic exercise as much as you can without flaring all seem to help.

if you have trouble holding up your head, exercises to strengthen the longus colli muscles will help, This muscle is often very weak in TOS patients. Gradually trying to increase the time you can be up will help as well.