My AM stafford has gas that smells like roten eggs.

Doggy gas is usually caused by food or by gulping or both. Try putting a rock or a ball in his dish when he eats – something he has to eat around – to keep him from gobbling. Make sure it’s big enough that he won’t accidentally eat it. If this helps, you’ve practically won the battle. Dish with obstacles in them are reasonably cheap & can be found at Petco.
If slowing down eating doesn’t help, you’ll need to look at his food. You’ll need to watch the carb content. My best suggestion is to go to the website for VeRUS Pet Foods & fill out the contact form. This will do 2 things for you: 1) you’ll get some really nice food samples for free; and 2) you’ll get some EXPERT advice on how to avoid doggy gas and what other things might be involved.
Truly, speaking from personal experience, I strongly recommend doing BOTH of these.

I recently took my Westie for his annual shots and mentioned to our vet that he was gassing us out of the house. Vet advised that wet food could cause it but gave us a prescription of Flagyl (sp?). Within 2 days the gas was gone and we realized he was so much more active. He apparently was suffering an intestinal thing but since bowels were normal we never suspected anything. Thank goodness the vet was on top of it!!

Try changing up his food, especially if you are feeding him cheap quality food. I had a dog with bad gas and allergies (for four years he had chronic yeast infections in his ear, and hated the ear drops the vet prescribed). While I was out of town, the kennel changed up his food and it made a world of difference. From that point forward I fed him nothing but Taste of the Wild dogfood, until he passed away at fifteen years, and it is still the only brand I feed my dogs.