Hi Desi,
My experience has been that if it causes more pain, it's ultimately not going to help me and might even make me worse. It was a physical therapist that aggressively treated my knees & caused the RSD spread there. I'm not saying that all PTs are bad, but I had a bad one. Prior to her, I had a good OT that treated the RSD in my hand. She did have me use a TENS at a very low level and constant modulation on my arm. She said the intent was to disrupt the pain gate. The TENS was not put on the RSD hand. I can't say that it really helped but sometimes I use it now on tense shoulder muscles. I've tried it on my sacro area but it makes the pain worse there.
I wish PTs knew more about RSD. I just don't trust them anymore. I hope yours can help you.
Linmarie