Chick fil a grilled nuggets and chicken noodle causes the runs, why?

Chick fil a used to be such a safe food for my GERD but after developing IBS it’s cutting out even what used to be my safe foods, idk what to eat anymore other than lean beef that been boiled or roasted at home with potatoes and an assortment of vegetables. It’s difficult because I don’t always have access to a stove.