So glad to hear K is doing so much better. Sorry to hear Baby G is now also showing signs of allergy. I'd say, given that dairy was K's main problem and caused those symptoms I'd start by cutting dairy out of your own diet and see if the symptoms improve. If they don't then you might have to do trial and error, but there's a good chance the milk is to blame.
really hope it improves quickly.
We're back on a wheat free (or significantly reduced wheat) diet with logan. And at the moment he's dairy free too though that's mainly due to a cough. I've actually put myself and dh on a mostly wheat free diet too as we notice various bad side effects from wheat (dh gets a very upset and crampy/bloated tummy, and I get headaches and blurry vision).
I think for all 3 of us though it's more due to intolerances than actual allergies.