Poor thing, that's horrible. Yes, I think if you had an immediate reaction like that your doc would be pretty sure it was a reaction to the penicillin.

I'm allergic and like you, developed it as an adult - was fine as a child. I vomit and also break out into a horrible rash. As others have said, erythromyacin and a couple of others have been fine to take instead.

Take care of yourself x