I want to share my story hoping some of the things I have learned will be helpful to you. This is how milk affects my family.
I repeatedly talked to my doctor about my oldest son who would have emotional break downs often. Years later we just decided he was an emotional kid until we took milk out of his diet after hearing it could help with bed wetting. It did not so we reintroduced it but minutes later my husband and I looked at each other with amazement, he was weeping profusely. We had not realized but he had not cried like this since we had taken him off milk.
Fast forward two years, some friends suggested raw milk but I was afraid to try it. I had avoided milk, yogurt, and ice cream for years and any of these would cause him to be emotion (very understated) for days and it affected his school work. But finally, after trying to keep his calcium intake up with vitamins and kale every other calcium rich food I gave him raw milk. And... it did not make him emotional.
I started looking into the reason and found that pastured (regular store bought milk) has been cook above 141 degrees. After this temperature the enzymes you body uses to digest the milk start to die off and so do many of the vitamins like Omega 3's. Many people notice an unset stomach and some don't notice anything but your body is over working to digest the milk without the enzymes.
So what does this have to do with night terrors? Well, a year after starting my one son on raw milk I went to the doctor about my other son, he was 3 yrs. old and having at least three night terrors a night about 20 minutes each and I was exhausted. The doctor said sometimes night terrors go hand in hand with food allergies and suggested taking milk out of his diet. I instead change him over to a raw milk diet as and all night terrors stopped. I was not having the entire family drink raw milk previous because it had to be purchased out of state, I live in NC, and it is expensive.
Since we started the raw milk my son has had a few night terrors, but his schedule was really off and we were out of town and off our routine.
I know you wrote this a long time ago but I assume you still have struggles with this since my oldest has been struggling for years. I hope this can answer some of your questions or anyone else who is struggling with milk reactions.