I have the exact same problem. It started 7 days after hernia surgery. I sat up in bed to stand and when I moved my left arm forward I felt a very sharp pain about 4 inches below my arm pit. The pain seems to be getting more intense daily. After about 4 days of pain on my left, I started having the same problems on my right side. The pain has been with me for a little over a week. Like you, very intense when I first get up and gradually don't feel it at all the remainder of the day. Unless, which I just discovered today, when riding my 4X4 ATV I feel the sharp pain on both side with every quick bump on the trail. I'm also noticing it in my car if I go over a good bump. Ouch! Any help would be greatly appreciated.