I'd be surprised if surgery is recommended. I doubt his intestine is protruding from the abdominal wall or anything like that.
sure sounds like it's inflamed, so there are several types of physio-therapy that can be used. Besides that, the scar tissue from surgery on a muscle the size of the abdomen can cause as much inflammation as the injury itself. Surgeries on muscles can weaken the muscle as often a strengthen it
my uneducated hunch is if the condition was severe enough to warrant surgery, he could not have played at all over the first 20 games