Thank you everyone for your answers! I really do appreciate it! I put my son back on almond milk the unsweetened kind and his horrible #2s have stopped. Also he isn't stimming in a frustrating way as wildly as when he was on regular milk during those couple days. Crazy what a difference food / drinks can make!

Coconut milk is also casein free

I have my son on almond and coconut milk (i switch back and forth ) . He does good with both. Coconut milk has over 40% of calcium and almond milk almost nothing on calcium .

We do almond milk but not sure if it casein or not. :/ I can tell the difference in my spectrum child when he has dairy. So I blame it on milk also. Dr usually start with a blood test but those almost always come out negative. Endocologist could do a full allergic panel.