It could also be remainder gas bubbles from the air used to inflate your torso during surgery. I had brutally sharp pain in my diaphragm for 7-10 days post surgery. The walking suggestion from the Dr is to just help move the air around so it can gradually work its way out of your system. My MIL used to be an ER nurse. She said they had so many people report to the ER w chest pains thinking it was a heart attack that one of the first questions they would ask was if the individual had recently had surgery to determine if it was actually gas/air pain.
