Have a read of Kellymom's info about Nursing Strike - you should express, either by hand or pump, both to relieve any pain and to maintain your supply.
You can then try to feed your DS your expressed milk with a cup or syringe. Kellymom has tons of info, but in brief get thee to bed for plenty of skin-to-skin with DS, try taking a bath with him. Lay him between your breasts and let him lead the way. Make sure you keep hands away from the back of his neck/head as babies can really object to any amount of 'force' or 'pressure' to the breast.
Walk him round, rock him (all with your bosoms dangling free), sometimes motion helps to encourage them back to the breast. Even if he's not actively nursing, it's important to keep him very close during a strike. He may be (I'm sure temporarily) 'off' your breast for some reason, so he'll need your warmth, smell and comfort all the more.
It's highly unlikely that anything in your diet is affecting him - babies ARE windy! They DO fart. A Lot some of them! They have an immature digestive system which creaks and groans and grumbles.
It can be incredibly distressing when a baby won't nurse. It can seem like a rejection. Just be gentle with yourself and your LO, follow the instructions on Kellymom, be patient and he'll come back to you.