With a family history of food intolerance I was already on the look out, I chose to be dairy and soy free since birth.
At 3 weeks old I know he had reflux - to me that meant that dairy intolerance was highly likely. At that time he was showing serious sings of lcatose overload or fermentation of the gut caused by food intolerance. His symptoms were yellow frothylloud squirty poos, lots of tummy pain and knee pulling up, grunting on and off for an hour after a feed in pain, lots of pain noises deep bearing down grunts after a feed. Lots of wind. Under a suggestion of my osteopath he said fermentation of gut due to either temporary lactose overload, yeast or gluten intolerance of all three. Immediately I started treating the lactose overload. He got quite a bit better aftyer a few weeks, but still the symptoms were there. Then I cut wheat and yeast and all the tummy soreness went. All the grunting disappeared. But I was left with the reflux and upper tract pain - gulping, hiccups, nose rubing, physical refluxing, wet burps, different pain noises!!!
A few weeks later I found some very unhappy poos after I ate a 6 egg omelete - spalttered on the nappy , yellow, smelling of eggs and very farty also he was unsettled the whole 24 hours after eating the omelete. I tried eggs a few more times and the same. So I cut them out.
We went ok for a motnh or so until I noticed that his poos had turned green and mucusy with stringy bits in them and he was sooo unsettled at the same tim with a sore tummy. I thought about salicylates, - DH is sensitive to them. I knew I was eating large quanitities of high sals foods (inplace of everything else I couldn't eat). So I decided to go on the RPAH elimination diet - that's the best way to test for natural food chem sensitivities, its very hard to tease it all apart, as the reactions are delayed and occur after eating a range of foods, not just one food like eggs.
Here we are a few months later and confirmed through food challenge that he is salicylate sensitive.
HTH