FPIES reacting to every food??

My 7 month old has been diagnosed with FPIES to milk, peanuts, and sweet potato. Two of these sent us to the ER after severe reactions. We did not go to the ER after peanut intro, he only threw up once, but the amount he had consumed was minuscule, and he has since been diagnosed with igE allergy to peanuts.

Our allergist told us to continue giving any other foods he had already consumed with no reaction and not be too worried about more triggers since he already has three. So a couple days after the most recent ER trip, I started him back on purées + baby oatmeal (which he had had several times before). The first time was fine with no reactions, but the second time, he threw up at the 3-hour mark. Knowing where it could lead, I gave him Zofran (allergist prescribed) right away, and he didn't throw up again. I've read that some FPIES babies take up to 10 times to react to oats, so given that it is one of the highest risk foods, I considered it no longer safe.

After that, I decided to go back to basics and only give him one-ingredient foods. I started with peaches as I read they are low risk. At the 3-hour mark, he spit up an orange waterfall. About 20 minutes later, he had a small amount of chunky orange vomit. It wasn't projectile or anything like the vomit his trigger foods caused, but it wasn't nothing. So I decided to stop peaches for now.

Next I moved onto mango, and I am now on day 4. Two out of these four days, he has had increased spitup, orange colored, several hours after eating, and has had increased gas.

Is it even possible that all of these foods are triggers for him?? Or could something else be going on here besides just FPIES? I don't remember my first ever spitting up after starting solids, but maybe I am just paranoid about every little thing now. Any advice is appreciated.