Spit Up

My baby is 15 weeks old and the past month has started to spit up more and more. We switched formula (was taking enfamil gentle ease and now is taking similac sensitive ) to see if that helped him at all. It has helped as he no longer screams after eating, and his eczema is clearing up but now he spits up chunky bits of formula hours after he ate (even when he is sitting up right) I should mention he is taking medicine for reflux. Do I call the doctor or just continue with the all babies spit up mindset? (He is gaining weight, he just spits up so much anyone who holds him needs a blanket as well to protect their clothes)