I'm no doctor but from my own experience I would venture a guess that your issue lies with the following statement you made:

"as long as I didn't move my arm excessively, the pain was manageable."

This is a common RSD trap and one I found myself in. You limit the movement because it doesn't hurt as much when you do that...but then the pain gets worse and it's BECAUSE you didn't move the RSD limb that much. Use it or lose it. I know it seems counter intuitive but that's the way that it is. After I first hurt my ankle prior to the RSD diagnosis they put me in one of those moon boot things to immobilize my leg. At first I thought it helped...but over time the pain just got much much worse. I now know that it was the immobilization and guarding that made it progress so much worse so much faster.

So my suggestion would be to go back to the doctor, discuss meds, and discuss other treatment options. I think you should look into physical therapy (if you can't go to an outpatient center then ask for at home physical therapy) as well as ultrasound and/or TENS treatments as part of that therapy. Anything you can do to keep moving. I would also suggest looking into desensitization. Hurt like all heck but was totally worth it for me because my sensitivity was SO bad before I did that. It's still not great but at least I can tolerate clothes now.

There are other things to look into as well in terms of pain management in addition to meds: tDCS, blocks, mirror therapy, ketamine, etc. Start with the least invasive first of course...but I would look into all the options and discuss a treatment plan with your doctor. Make sure you educate yourself about the risks and benefits of all the options and never let yourself be bullied into a decision you are not 100% comfortable with or make a decision in desperation.

I'm so sorry to hear about everything you are going through. Don't give up hope of help. It's a long, hard road but there are options out there and hopefully one will work for you. Take care.