Drink a seltzer water really fast. It will push the gas out. Or you can sit/squat and rock back and forth an it will help move the gas . That's what usually helps me
As much as I'm sure the pressure is hurting since I was like that yesterday, I suggest getting up an walking around a bit and releasing whatever gas needs to come out. I was always told by my mom that has pains us so much cuz it's trying to move around food that's slowly digesting down there still and walking helps with digestion. It usually helps me to walk around. And I agree with the tums advice, it helps! Steer clear of foods for the day that make you gassy too and if you're around people (at home at least) carry some air freshener lol us preggo ladies tend to have some smelly releases! Lol
The only thing I can say is to let it out and not hold it in if you can help it. Drinking tea always helps with gas, and you may not want to take anything, but TUMS does wonders. Hope this helps...