What's in that coffee?

I like coffee but it doesn't like me. I switched to decaf some 15 years ago on the advice of my doctor. Unfortunately, some brands of decaf make me ill and I can't determine exactly why. Two likely culprits are:

1. Some chemical used in the process that removes caffeine.
2. Some other chemical added to the coffee.

I am okay with organic decaf and probably some other kinds. Generally I stay away from flavored coffees because they cause me extreme chest pain. I once wound up in the emergency room thinking I had a heart attack after drinking flavored coffee at a social event!

Most flavored coffees contain propylene glycol, a "non-toxic" antifreeze. I suspect I am sensitive to this chemical. But avoiding flavored coffee is not enough. Lately some of the supposedly unflavored coffees have been giving me sharp pain in my abdomen, and it lasts for hours. Now I'm afraid to enjoy a cup of decaf in a restaurant because I have no way of knowing what's in it. I stopped drinking McDonalds decaf years ago because it gave me chest pain, but the ingredient list on their website shows only coffee. (I don't use the creamer, which lists a lot of chemicals.)

Unfortunately, propylene glycol is considered a safe additive and is not always listed on cans of coffee, as far as I can tell. So for now I am sticking to organic decaf, even though it is expensive.