Reading labels has helped me avoid many problems with food intolerances. Its a pain, but not as big a pain as being sick
I bought some Tropicana OJ right before you posted your message. But, I've never had a reaction like that. Plenty of other reactions though
I've found that educating myself and learning all the names for "harmful" items has been a big help for me.
I am glad to hear that you have found the sources of your problems. Its not pleasant, but it is a huge step toward finding ways to live with the problems.
Nikki