My Daughter Is 21 And Experiences Redness Of The Face

My daughter is 21 and experiences redness of the face and neck (blotchy flushing) with minor swelling after eating.....starchy foods (potatoes, etc) seem to often be what she has eaten before it happens. She also has dizzy spells (feeling faint) not at the same time as the flushing. She also has extreme temperature differences between her lower extremities. One foot or hand can be ice cold while the other is red and hot.