Severe Back Pain With Swelling. Strained Muscle?

I been having really bad back pain ever since a wreck I got into 2 & a half years ago. At first after the wreck, I didn't have any pain until 2 weeks after the wreck. A muscle in the left side of my lower back swelled really bad & hurting so much I'd cry in pain. Well I went to my normal doctor, he said I strained my muscle & gave me painkillers & said the pain will leave in about 2 weeks. 2 & a half years later I am still in constant pain. I cannot stand too long, basically I can't do anything (not even lay in bed for a long period of time) without the muscle swelling up & hurting. Sometimes it swells so bad; the swelling starts to go on top my spine which really scares me. I don't know how to describe this pain, but I know if I or somebody touches the back muscle just right, it sends me to the floor in pain! Please help me figure out what this is because apparently my doctor doesn't know. Again, its the middle-lower left side of my back.