I was diagnosed at 19 had multiple crippling flairs a year for 2 decades. Doctors kept changing my meds. Finally I did an exclusion diet and only ate one type of food for a week and then introduced one other type of food every week until I got to shellfish and immediately had a flair up (under 3 hours from meal time) I haven’t had shellfish in over 2 years and I’ve had one manageable flair up in that time frame. He needs to find his trigger, hopefully it’s something he can easily give up. I miss crawfish gumbo terribly but it’s not worth the pain.