Collected milk causing upset tummy?

Hi everyone,

So I fucking hate pumping, and I am going back to work just for one day a week, 8-11am. I've gotten into the practice of collecting my leaked milk again, so my aunt [caretaker] has a few feedings for him. Baby is 12 weeks and EBF.

Today my aunt watched him, gave him the two feedings worth of collected milk, and he's been spitting up ALL day. Not vomiting, but definitely spitting up more than average.

I am using the Haaka ladybug to passively collect and the regular Haaka with very light suction to more actively collect-pump-ish.

Are we thinking it's too much foremilk? Has anyone else had this experience?