Sulfites are present in lesser amounts in mashed potatoes made from dry powder, pickles, tinned shrimp, cookies, crackers, and readymade pie dough.
have been taking
these things in a good amount, then cut down the intake. Also take a lactobacillus preparation and yoghurt with your meals (you are already doing this). In all probability the smell will go. If it persists, then talk to your doctor. Get your self tested for hypothyroidism and diabetes as this slows down the gut.