Why does drinking chocolate milk make me feel sick?

I’ve always seemed to notice this. It doesn’t happen all the time, but it does happen quite a bit. I have a feeling its when I drink a lot of chocolate milk in a small period of time.

I don’t really drink milk alone, but I have it with cereal and I feel fine. I also think this sickness happens with strawberry milkshake which makes me believe it could be a quantities thing.

Does anyone else have experience of drinking too much milk make you feel ill?