I just don’t understand?! And I might be missing something but surely we would be expecting some sort of bowel change when introducing something other than milk?!
For allergy you are looking for combination of symptoms really, skin/ digestive/ respiritory & nose and eye. Sometimes like you said they are getting used to a food or there are some signs but it can be hard to tell. It's trial and error really, take the food out and re introduce and symptoms track again, baby may develop a worse reaction each time if they have an allergy or may tolerate better each time or symptoms may be the same and they have an intolerance. It's really not a clear cut thing unfortunately!!
Following. Great question