Hi Oanh, my luv. Sorry you have found your way over here but we are here to support you through this. xx
I have to agree with the others. As you know I have followed Jack's NWs with you for months now and having read through other posts about toddler's sleep, for you still be be suffering them I would be guessing there is something else at play here. FWIW, now Olly is off dairy, wheat and eggs he is starting to sleep much better
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You say you have an appt with a Paed soon? That is a good start as they should be able to arrange tests for you - blood and/or scratch tests.
Milk is in so many things, things like the flavourings for crisps/chips etc. I think you need to take a very close look at Jack's diet and pare it back really. It is hard at first but you will get used to it.
Find yourself a good milk substitute - rice, hemp, oat - pref something with added calcium and make sure he is getting a couple of protein portions a day (my dietician rec'd this the other day for Olly so am passing it on!).
Good luck. Let us know how you get on at the Paed.