Muscle Strain or worse?

Patient: Hello,I recently (84 hours ago) took a knee to the back during a soccer game, resulting in immediate pain in the affected area. I continued to play through this pain for the remaining 30 minutes of the game.Nearly an hour after the game ended, I began having severe muscle spasms, that felt as if my back was tightening on the affected side. (Lower right side). It has, as mentioned, been 84 hours, yet I am still feeling the same muscle spasms, of similar severity, whenever I extend more than roughly 25 degrees to the right.I have a soccer cup final I must be prepared for in 12 days, are there any methods to work this hopeful strain out before my game?Thanks!Sebastian C