Binding doesn't work for me either, so I know where you're coming from. But, if two binders is causing this severe pain, why not just let loose some and just wear one properly fitting binder? Maybe put on a compression shirt over it. At least spend like a day or more per week without a binder on for at least most of the day if you can and do some good arm stretches.
Maybe you should see a massage therapist about your arm. My sister worked at a Massage Envy over in D.C. and she said it's pretty cheap to get a 30 minute massage, only $50. Or, go see a doctor.
If you insist on continuing to double bind, I'd try to incorporate a stretching routine in every morning and night before and after you take off your binders. There's also these weird looking foam cylinders with noobs sticking up on them (you can find it with the yoga gear at Target, or on their website
http://www.target.com/p/gaiam-national-ora-restore-foam-roll-12-inch/-/A-14071609#prodSlot=medium_2_8) that you're supposed to roll your back on, that could help to massage/relieve tension where you bind without having to pay for a massage every time.
Oh... also this stuff called Biofreeze works wonders! You can get it at a chiropractors office and I've also seen it at medical supply stores (they don't sell it in regular pharmacies like CVS or Walgreens).
