Yesterday, while playing with my friend's kids, I somehow hurt my back.  It was not too painful yesterday, and I thought it would go away.

This morning I woke up and had to walk hunched over with my hands on my knees or crawl so it wouldn't spasm.  I know I did something bad now, but geez...

My right thigh has some soreness as well.  And it's the right side of my lower back.  Wife is getting me advil and a back brace from the store right now.  Any ideas what I have done to myself?  this sucks.

You say that you,"somehow hurt my back."
I guess you can't then recall one specific event that may have caused it, so it may be just a muscle pull or spasm. Get some rest, let your wife continue to treat it.

If you can feel pain going down the side of your leg, then there is nerve involvement, and it is probably a ruptured disc. You don't mention this symptom, so that is unlikely.

If it doesn't improve, see the doctor.

I would recommend going to a chiropractor (see my post a few days ago in GD). I feel 100% better after about 5 visits. Many GP doctors will just give you medication to ease the pain, without getting to the cause of the problem. Other than ice, and a couple of motrin once in awhile, my relief has all come from the chiropractor. You have nothing to lose, except the pain of course!!!!Good luck!!PS he has put me on an exercise program also...