Did you see Akira Fujii's EMC lecture? He has some amazing theories on the muscle pass, and they only require an inch or so of "lift."
I can't do too much in the way of an "anti-gravity" coin, but I use the muscle pass for a number of other things that I learned from Akira Fujii's lecture and as part of a coins across routine where I shoot the coin horizontally instead of vertically.
If your hand hurts, it seems like you wouldn't be able to feel where you were messing up. I'd back off and let your hand recover, that way you can feel what's going on and make adjustments to the position of the coin, and other aspects of doing the move.
I'm no expert in this, so if other people have advice, take theirs into consideration as well.