Agree that seeing an allergist is a good next step. Labs, potentially additional allergy testing might help. But this is also a situation where history and physical exam are often pivotal.

I see chronic urticaria every day (hives), and most people want to know what they are allergic to… but the reality is that chronic urticaria is almost never an allergic reaction.

The paint may be your wife’s issue here, and patch testing may be key.