Lactose free cheese vs Lactose free milk...

I'm trying to work out what's going on with my 7 year old. She's had a problem with dairy since a baby. However she has grown out of some of it. She now can eat lactose free cheese with no issues. However lactose free cows milk still gives her problems. Does anyone know why this could be happening?

I have also tried her on goats milk which gave her a pretty bad reaction so I know she can't have that.

I'm just a bit confused as to why she's fine on lactose free cheese but not on lactose free milk.

Thanks. Tweet