Question about throw up/allergies

So my son is about to turn 1. The first time he had yogurt he swelled up and got red marks around his mouth. We waited a little bit and tried again after a few weeks and he was able to have a few bites and was totally fine. His stool was a little more mushy the next movement. Today I gave him 3 bites and he threw it up (plus some food). Does this seem like an allergy? Or could he have just been sick today? He doesn’t have a fever and has been acting fine.