A patient presents complaining of itchiness and trouble swallowing and breathing whenever she eats peanuts. who should see this patient?

The correct answer is an immunologist.

Reaction to peanut such as itchiness, trouble in swallowing and breathing are the signs of peanut allergies.

It is descried as type I hypersensitivity (reexposure to antigen-allergen) reaction of the immune system in susceptible individuals. So, diseases that affect immune system such as allergies are concern of an immunologist.