Dairy allergies?

For those of you who are dairy free for your LO’s… how did you know for sure they had an allergy?

My LO is 5 weeks and I’ve been EP and feeding him BM the whole time. We have never had to supplement any formula.

In the last 2/3 days, LO has been really fighting being burped. He tries to throw himself back and wails until his face is beet red. He is also spitting up more often. Sometimes it has more solids in it than others, whereas before it was usually pretty liquid with a few solids.

As soon as the bottle is out of his mouth he starts, even if he is the one who stops suckling or pushes it out with his tongue. Which is another thing that has ramped up in the last few days… he almost gnaws on the nipple of his bottle, just pushes it around with his tongue but doesn’t want to latch on. And then we’re back to him screaming.

The only changes I suppose I’ve made in the last 3 days are that I’ve been drinking a Body Armour drink a day to try to stay better hydrated and I’ve been needing to use Miralax for myself. Besides that my diet has stayed the same.

LO is still having his usual bowel movements… sharts throughout the day and 1-2 actual poops. The colour and consistency seems the same. My cousin learned of her son’s peanut allergies via her BM because his stool was foamy, green and always a blow out. My LO doesn’t have anything like that. LO is still wetting his diaper normally.

The big reason I ask if because although these changes have happened in the last couple days, LO has never been a big fan of us touching his belly. We’ve tried giving him gentle massages to help him get his gas/stool out and he wails. The only time he seems okay with it is in the tub.

What do you all think? I am a FTM and dealing with PPA but I also want to do what’s best for LO.