SO sorry to hear about everything you are dealing with right now, Cricket! I hope things get better for you soon!
I have been diagnosed with a condition called POTS which is a quick lowering of the blood pressure caused by a heart problem. My PM Doc says it is caused by my RSD and unfortunately, there's nothing they can really do about it. My blood pressure isn't always low (it just fluctuates) so that means that blood pressure medications wouldn't help.
The POTS causes me to collapse a lot. I used to faint around 20 times a day, meaning I couldn't go to school or out with friends. I've fainted in the shopping mall, movies etc so it's really embarrassing and scary!
Recently in PT my PTs also found out that my heart rate is twice the rate it should be. Simple tasks cause me to get out of breath really easily. I never suffered from that before having RSD so they are wanting to check it out and send me to a Cardiologist.
Sorry I can't help you much. Just know you aren't alone and if you ever want someone to talk to i'm here.
Alison x