Excess gas from surgery or digestive problems travels up and can get trapped in your shoulder, irritate the nerves in your shoulder and make you very very miserable. The pain can be a deep ache or sharp debilitating pain and come on very suddenly. Here is what I have found that helps me. Do some of the yoga poses at the link below. First I do the downward facing dog or any pose that gets your torso upside down. Then I do the knees to chest pose while laying on back and I do that several times. Then, lay on left side for a few minutes. I also take 3 or 4 galviscon tablets or generic equivalent. Gasx doesnt seem to help much once the severe shoulder pain has begun. The gaviscon (or generic) is very soothing. For the longest time I thought it must be my back because I do have back issues or I must have ripped something in my shoulder so I was eating tons of Advil and naproxen sodium pills whuch just made issues worse. So give it a try - it may be helpful. Here is the link to the yoga poses
http://www.popsugar.com/fitness/Debloating-Yoga-Poses-30797559
To avoid this, I try to not eat things that do not agree with me, don't overeat and don't eat close to bed time.
not sure what you mean gas pain
our body's make muscle nots called trigger points that have toxins in them and takes massage and lots of pressure to work knots out enough toxin that you need lots of water to was out gas i would see doc