The stomach pain and the gas you're experiencing make me think that maybe you have a hiatal hernia, but DON'T WORRY - a hiatal hernia is not a big deal and it is a very common medical condition. The reason I'm telling you about this is because I know firsthand how uncomfortable stomach problems can be, and if you do in fact have a hernia, you should know about it so that you fix the problem. Maybe you already know this, but a hiatal hernia is when part of the stomach is pushed upwards through the diaphragm into the chest cavity (sounds worse than it is). Heavy straining, weight lifting, and being overweight can contribute to the development of a hiatal hernia. I would suggest that you arrange for an upper GI series (x-rays of the stomach and surrounding area), this is the only way that I know of to diagnose a hiatal hernia. And if they run an upper GI series and find nothing, that means that you definitely do not have a hiatal hernia - in other words, the test is conclusive.
Because this is a health anxiety forum, I would never tell anybody that I thought they might have a serious health condition. The reason I'm telling you about the hiatal hernia is because it is NOT a serious problem and should not cause any panic whatsoever. However, if you do have a hernia, it's something you should know about because there are many things you can do that will help to reduce the symptoms.
BTW, I have a hiatal hernia myself and so does my father. By taking Pariet every day and losing weight, I've managed to reduce the symptoms by 95% and feel much much better. Upper GI series have confirmed that the hernia is getting smaller and smaller and, over time, it will probably go away completely. Like I said before, it is not a serious condition and is definitely not life-threatening.