00camper,
Brother, I feel your pain.
I have a bad back, arthritic disks. There is some good advice in this thread, however, see a medical doctor first. I say this to get a medical evaluation of your problem. There are many causes of back pain, muscles, tendons, bones, disks, even stress, and combinations. After that, find what works for you, and avoid doing the things that hurt your back.
I can add, get at the pain right away. The longer it goes, the more muscles tighten up and the more miserable you will be. Too much heat got me stuck in bed, causing more than one ambulance ride to the emergency room.
The very best advice I can give you is, NEVER pick up anything heavier than a six-pack again.