I get these knot/spasm things in my back pretty often and they are extremely painful. My entire back will seize up and I can't turn my head at all. Smoking does help me quite a bit but I'm smoking super chronic medical marijuana. I'm not sure how much good mids or schwagg would do. Also, I've found that an indica strain helps much more than a sativa strain.

Other than smoking I have found that acupuncture helps a lot. It's pretty bizarre, you feel like a human voodoo doll with all these pins sticking in you, but it works miracles. I live in the San Francisco area so there are a lot of good Chinese acupuncture docs around. . If you have any where you are its worth looking into.

Other than that, warmth helps. Take a long warm shower. Or, fill a big ziplock freezer bag with rice or beans and put in the microwave for 2 minutes. Wrap it in a towel (or it'll be too hot) and just put it behind your back. The bag full of rice actually works better and stays hot longer than any fancy thing you can buy.

Hope that helps.