The pain that you are feeling in your left shoulder is gas. I too have this left shoulder pain although I am right handed I can't sit up for long periods of time without the pain getting the best of me. It is said that it can last 3 to 6 weeks after surgery. Try a gas tablet like Gas-X or Gaviscon and a heating pad this seems to work pretty good. Doing better now one week post surgery. Can't wait to return to work.l I have not weighed myself first f/up is 8/12. Have a great day today.