Pain moving from back to sides?

About two weeks ago I started feeling pain in the lower right of my back, the next day it moved to the center of my back and I could hardly stand up. Now the pain is shifting more to my left side, under my ribs, just above my hips. I thought this was from a pulled muscle from helping a friend change tires on his truck and tossing them around, but its lasted much longer than anticipated. The pain began the day after changing the tires and has not weakened, just moved through my lower back. Moving around causes it to get worse, and its more of a dull pressure pain, although it is powerful enough to keep me from kneeling or bending over. Any suggestions would be appreciated!