Baby being sick

My baby is 11 weeks old and for the past 3-4 weeks she's been puking up nearly her entire morning bottle - every bottle until like 1-2, By like 2pm, its just occasional spit up?! Ive tried pace feeding, burping inbetween, keeping her sat up for like 30 mins to an hour after Nothing seems to be working We're even using co-lactose drops to dissolve the lactose in the milk incase its that Its stopped her from getting a stomach ache but thats it Any suggestions please 😭