These are the secrets that no one tells you- you have to live through them and figure it out when you have your own children.
We do not have allergies in my family, no exposure at all. However I knew about food intolerance- I have always reacted to cow dairy milk and yogurt with bad cramps and gastro distress so I stayed away. But I loved cheese and ice cream, even though they gave me mild bloating which I would ignore for the pleasure of the taste.
Looking back, it makes complete sense that both my boys inherited my dairy intolerance because thats how it works, mommy passes all microbiome and sensitivities to children, but I knew nothing of that way back then. My first child was restless, unhappy, fussy- he needed to be held and rocked all the time. He would sometimes scream and curl up into a ball seemingly in pain- colic they called it. So we tried everything - gripe water, massage, warm towel on belly- but the most he would sleep was 3 hours at a time, all around the clock. We tried music, white noise, fans, rocking crib, co-sleep, complete dark room and quiet- funny how you try everything to get a baby to sleep- we even disconnected the front doorbell. We were exhausted but we managed.
My second joined us fifteen months later, he made the first look like an angel. He would only sleep when moving in the swing or being held, and for an hour or two at most. Even worse colic they said, sleep became a distant memory as we turned into zombies. Lack of sleep impacts your appetite, mood, memory, everything- I remember finding pots boiling on the stove having no clue when I started cooking. These things started to add up, and we were left considering extended leave or outside help.
That was when we started looking for answers. I started to pay attention to what I ate and how he reacted to my breast milk- sure enough, that dairy I was still eating was causing him pain. Things got better when I removed it from my meals, but only a little. He would also react to a growing list as I whittled down my diet until I was eating only salad, again not sustainable. Then I thought perhaps it was the milk itself they he just could not tolerate- no one agreed with me. We went out and bought a sample of every kind of formula on the shelf and tried them all- he could not tolerate any of them, until we came to soy. And there was our magic answer, I was right. He could not tolerate any form of dairy protein, and did just fine on soy for the first year until solids. I also took my first child off all dairy too, and he got better as well, his little belly bloat, crankiness, pain and gas finally went away. Sleep became wonderful again, for the whole family.
The secret I have learned is to trust your mommy instincts, even when all those around you say otherwise, including professionals. Don't wait until things get really bad to start looking for other alternative answers. You have the closest connection to your baby over all else, so listen to that little voice in your heart when in doubt. Persist in looking for answers because you will find them in places that will surprise you.