that's interesting, because a lot of people use marijuana to dull pain. the only thing i can think of is that my muscles get tight and/or spasm sometimes when i get high, especially when i used to do it many times a day. so it makes sense that if you injured your muscles, having them involuntarily tighten could be pretty painful. i would suggest getting some physical therapy (if you're not already) and maybe even yoga or pilates or something where you can stretch your muscles out so they don't hurt when they tighten.