Thanks for the comments guys. I just got back from the doctor. He says that I could have fractured a rib, but that there is no treatment for it. He said if the hip is much worse in the morning then I should go back in and get x-rays. Otherwise, 2 days off from work. (yea right)

I think I'll try the bungie on the panneirs. Actually, I may bolt on some rigid sides to the rack. This is the first problem I have had with my panniers. I'm normally loaded to some extent which keeps them from moving around much. Lesson learned.