Wendy, the only reason I had suggested dairy free to you was because of Finn's constant runny nose. Not his sleep issues. Despite him being an EW, he doesn't generally have bad or frequent NWs. The kiddos I've seen with food allergies often get NWs as one of the symptoms, though not always.
But to really know, Laura, you'd really need to try totally soy and dairy free for at least two weeks.
Sarah, I'd think any good grocery store would have canned coconut milk with the Asian foods. You can open a can, pour it into a tupperware or pitcher and keep in fridge, shaking and pouring a few ounces into a bottle or cup as needed. BTW - DS is totally waking from naps (and most mornings) sobbing too. HATE teeth!