Cow’s milk protein allergy?

My 3 month old baby keeps getting diaper rash despite properly care and change 2-3 hourly. I stopped using all wipes and only water. Changed from pampers premium to Merries. I noticed she does pass small amount of motion throughout the day. She is taking nan pro ha 1. I am beginning to suspect cow’s milk protein allergy. Anyone here with similar experience or tried Alfare before? Thank you