10 week old - spitting up a lot

Our 10 week old has been solely formula fed with Gerber Good Start Gentle. since late December and has been doing great with it with no issues for a month. Until recently, he has spitting up a ton after feedings. We don’t think it’s reflux and isn’t fussy when he’s spitting up but sometimes fussy after a bottle. Could it be that we need to try a new formula? I find it hard to believe that we’re over feeding him because he was fine before with the same amount that we had been giving him. Help please!