FPIES and modular formulas?

Hi there…so after 2 months of mulitple failed formulas and continued GI symptoms, the GI thinks my babe may have FPIES (this is food protein induced enterocoltits syndrome) He is 3.5 months old. We are having an endoscopy and flex sigmoid next week to evaluate whats going on in there. He does not have the “classic” symptoms of the fpies, with the severe vomiting and shock, etc. What he does have is awful reflux, nasal congestion, spitting up mucus, very thick mucus in his stool which is very difficult to pass, and blood in his stools. his belly always seems to hurt. he does not do well on elemental formulas…