Welcome to the forum, minisab5.
There's no recognized test for sulfite intolerance. Keeping the "food journal" is a really good way of documenting and detecting your "food triggers" though.
I react to tapioca pudding (Minute Tapioca) pretty strongly and my reaction is the one I get from sulfite, and I use lactose-free milk. (lactose intolerant too)
Here's a website from Australia manufacturer talking about
how tapioca is made. They say it's processed with potassium metabisulfite. sillyyaks.com.au/faqs/do-your-products-contain-added-sulphites/
Other websites, like a Bob's Red Mill ad, say their tapioca does not have any sulfite. I may try again with this product because I love tapioca pudding. Just don't flavor with ginger or any other spice known for sulfite.
Rick's book, the paper one, lists Minute tapioca as having 16 mcg sulfite per 1 teaspoonful.
There are plenty of good foods that are sulfite-free! We just don't get to take too many shortcuts, like processed foods. Even veggies that have some sulfite aren't all horrible. I'm not highly intolerant, but I can get away with some broccoli. Carrots, salads with home-made dressings are good. Just use frozen lemon juice instead of bottled to add to your oil of choice. Rice vinegar is supposed to be clean too. I only use a tiny bit.
Avoid potato starch or anything processed from potatoes, although a nice baked potato is clean and delicious. Same with corn. It's fine unprocessed, but avoid anything with corn starch, dextrose, etc.
There are some rice cereals that are clean, but avoid the ones with brown sugar or molasses.
I don't have a problem with a little barley, but have cut down on wheat a lot. I think I've just gotten a wheat intolerant, not allergic, suspect the modified grain, but no proof.
Exercise is good for many ailments. Wish I could do more.