I've been there with back/shooting pain in my right leg so severe I could hardly walk. I could sit, or lay down, but walking was beyond me. I went back and forth with my PCP: xrays, therapy, etc. It got to the point finally that I went to ER. Even they gave me a rough time, until the MRI results. Then they were all nicey nicey and do you need something for the pain. I did end up having 2 back surgeries and have residual nerve damage, but I can walk. It was most definatly a repetative lifting injury, but the worknan's comp person told me he'd fight it, and I didn't want to deal with that, so I didn't file a claim. In retrospect, though I didn't have 1 incident that I could blame it on, I should have persued workman's comp.
I am returned to work full duty although my surgeon recommended permanent restrictions. I still have back pain, but it's not constant and seems to respond to vicodin well.