Well, my first reaction would be to switch back to the old food and see if you notice a difference.
My second thought is: Is his bowl on the floor or elevated on a food stand? Our German Shepherd had gas problems and then we got an elevated dog food stand (you can get them anywhere) and it stopped the gas.
Is his poop okay?? Any diarrhea at all?? Does he it it fast? If he's a fast eater put a small heavy bowl upside-down in his bowl and put the food around it and then he has to use his tongue slower to get the food so he chews it more than swallows it whole. Some vets recommend a big rock too, and I know they make special bowls for this problem too, I just don't know how much they are.
I hope some of this helped, if not, I'm sorry!!
All else fails, ask your vet. Good luck and I hope your pup feels better soon, it's no fun being gassy!