How old is your boy?
what was the prior canned food?
Intestinal gas is vey comon in older cats because their digestion is not as effective as when they are younger. They also do not chew as well as they used to. Give your boy a teaspoon of plain yogurt every day. That contains acidopholus and will keep "good" bacteria in his colon which will control excess gas. If he will not eat it or it is not strong enough you can get a probiotic for cats in liquid form at a human health food store.
At his age, feed him whatever he loves and will eat so his caloric intake does not change. Most cats (mine included) are crazy about fancy feast.If he is not ovwrweight you can give him dry food for kittens as the pieces are smaller and easier to chew.
Please let me know how he is doing and if you still have questions. I will help in any way possible.
Sincerest best wishes,