Have you tried going off soy, which is in a ton of foods? I've just been looking up studies and it ranges from 0-63% of kids with milk intolerance also have soy intolerance (both my kids have it along with other foods). It can be any food really. Have you tried going on an elimination diet or a TED? Have you kept a food journal? If it's with every meal then it's probably something you eat frequently. My DS was a projectiler as well (it was amusing a few times -- very few times -- when he went over my shoulder and DH, 5 feet away, had to jump to avoid being hit was one of them that stands out) during and after every meal. He was diagnosed as having reflux though all the reflux symptoms went away when I eliminated milk. But when he started directly ingesting soy, he was intolerant to that too. Just because things don't show up on an IgE test, doesn't mean he doesn't have intolerances. If you already have allergies in the family, it's likely that he has one or the other. You just have to determine the triggers. Many of us have been where you are...