As far as the symptoms of inflamed gallbladder
are concerned, as per my opinion it doesnot present with blood vomiting
. As you did mention that he has been scuba diving, there is a chance that it has something to do with that also. As far as going in for surgery is concerned, i dont think its an emergency situation as far as inflamed gallbladder is concerned which can also be treated conservatively. Advise would be to get complete blood profile done and if possible to get an upper gastroscopy to rule out any pathology within the upper gastrointestinal tract. Regards.