i have been having really bad gas pains too and if its a reluctant one to be released i get on my hands and knees. lower my upper body to the ground so my butt is in the air and just sit and relax like that for a few minutes. its a trick for boys on a hot date who have gas and need to release it quickly. : )
hope that helps a bit.
Gas pains in pregnancy are killer! You may feel it all over as your intestines snake around in your belly so it definitely could start in your back and move to the front. I just read the blog of an OBGYN nurse who said they had a woman come in and she was in so much abdominal pain (she was early, too, 1st trimester) and then the lady just let one and was fine. So I wouldn't go to the OBGYN for that... see if relieving yourself helps with all the pressure!