food allergies

Did you feed your baby that gave them any allergic reaction? What happened and how long did it last? I introduce plain yogurt to my son other day. Gave him maybe 3tsp and he actually like it. That night he had a rash on his face only. The next day, rash was cleared but then diarrhea started. I EBF. Everytime i nursed he made dirty wet diapers. No fever but starting to get irritable because he didnt get enough sleep.