My surgery was July 13. I am a nurse so I thought I would have a better knowledge of what to expect. WRONG! I too had a hiatal hernia. I had tons of gas which has given me more pain than the actual surgery. I found that Phazyme gas pills have the most medicine in each pill and they are tiny. You only take them twice daily. I had been using Gas X and found they didn't have much med in them.
Do remember to take deep breaths to expand your lungs. It will hurt but the alternative is pneumonia. I was very close since I developed fluid in the bottom of my lungs. I had to cough to clear this. That was total pain. I still have shoulder pain from the gas but it is getting better.
Take comfort in knowing that you are not alone. There are many more who are feeling your same pain.
Best wishes to you.