Mild rash from eating mushrooms?

My wife has allergies to shellfish and hot peppers, but we thought that was all. This week about 2 days after eating portabella mushroom and a day after eating oyster mushrooms she developed a rash on either side of her mouth she says makes her look like the Joker. All the info Ive read says mushroom allergies are quick to happen (not 2-3 days) and are not located only in one spot. We can't figure out what she's eaten that would do this. I take great care in cleaning/ checking everything to avoid anything she is allergic to coming in contact with her. Mushrooms are the only new food she's had, but she's eaten them in other types of dishes. Help?