I'll look into the allergy idea. He really only drinks water and the occasional cammomile or green tea on a regular basis, and we rarely eat out of have anything with MSG, so I don't think those are the problem. And my health problems are really different from his, and I know what's causing them--stress. It could be the same for him, but I want to rule out everything it could be, so it's good to have more ideas. It just really seems to be a random occurrence.
He'll be going to our primary doctor soon, and he's integrative, so he has an alternative perspective. He's also certified in allergies. And I definitely want him to go to some specialists, too.