DON'T do anything that causes it to hurt - it's that simple. Unfortunately, you're doing exactly the wrong kind of work. I know it's a practical issue of money, but aggravating it could lead to a much more serious and permanent injury. I broke my back last October, and then again this June. They didn't do surgery, but P.T. instead. The point is, if it hurts, that means you're doing damage. It doesn't sound like it's broken, but you really should have it x-rayed. I appeared normal, I could walk, sit and stand OK - but certain awkward moves caused blinding, phenomenal, crippling, excruciating pain beyond description - If I was standing or walking when it happened, I would involuntarily drop to the ground like a sack of potatoes. It's no fun - don't risk it by doing heavy lifting. Ask your job(s) if they can give you something less demanding to do for just a couple of weeks.