Either one can help a lot or aggrevate the problem depending on what the problem is. It sounds like a nerve issue that is in your neck and is radiating down through your arm... I had the same problem years ago after a car accident and sometimes it flairs up a little to this day. A good chiropractor could help things a whole lot.
One thing that helped me was an infrared heat lamp. The chiropractor would have a big one, but you can get a handheld one pretty cheap that you can use whenever and where ever you want. Unlike a heating pad, which only helps the surface tissues, it penetrates deep into the muscles. It also doesn't get too hot which can be a problem with a heating pad (you can actually burn yourself with a heating pad). Even if the problem is nerve related, much of the pain can be relieved with an infrared heat lamp because a pinched or otherwise aggrevated nerve causes the surrounding muscles to tighten... vertebrae minutely shifts, and that just makes it worse. A mild muscle relaxant like Parafon Forte can help, but the side effects can be a problem, and frankly, I got just as much relief from the infrared heat lamp that I did from the medication. Some muscle relaxants can't be mixed with other common popular medications, so be VERY careful that if you get a prescription, your doctor knows what other meds you take or may take while you're on the muscle relaxant... some drug combinations can kill you.
http://www.chiswingusa.com/infrarex.htmthis one is almost identical to the one I have... mine was about half that price though. Clairol made it, but I've had mine for years and don't know if they still make them.
Accupuncture can help a lot. My chiropractor used to do accupuncture on me with a laser... you don't feel a damn thing but the relief is instanteous, nearly total and lasted awhile. Accupressure was somewhat helpful, too, and some things you can do yourself (also helped a LOT for my psycho mentrual cramps from hell).
Oddly enough, it may even be a tooth problem especially if you get any jaw pain or pain in the ear area. But I've had the same symptoms as you before and it turned out to be a tooth, and I never had any jaw or facial pain.
Best of luck, buddy... been there, and it royally sucks. :(