How fast after eatting something that is a potential food allergy trigger will you be able to see a reaction inyour baby? I ask because the last two days I have eatten cookies with pecans and 2 pieces of millionaires pie with pecans. I noticed last night that my DS (almost 4 months old) had rosey cheeks. My older son and husband have food allergies so I try to keep track if I eat something different. The pecans were the only thing different.