What Causes Weight Gain And Headache In A Person Inherited With MEN 2-A Gene?

Hello, yes thank you. My daughter has inherited the MEN II-A gene, had her thyroid removed age 5, and recently aged out of Peds oncology. Her new physician had a calcitonin level drawn in office, and, based on the finding, has sent scripts for ACTH, cortisol and IGF-1 levels, as well as 24hr urine for catecholimines, VMA and metanephrines. Daughter has had fairly rapid 40 lb weight GAIN, not loss, and her diastolic runs now in mid 80s (84, 86). I am suspicious of potential pheochromocytoma but how would that explain weight gain? Other sx include sweating and headache. No palpitations reported. Thanks for your feedback, if anyone is endocrine expert out there.