Why do i get sick every time i eat barbecue?

Every time i eat barbecue i get sick.Whether it be a large headache or vomiting.I have had this experience more than five times each a different restaurant.Ive eaten pulled pork and beef brisket from places like bonos,sonys, and the last time was firehouse subs.Can anyone help me out on this matter.I really enjoyed the firehouse beef brisket sub and i want another one but not at the expense of the hospital.