Spit up after every feed

Hi my LO is 2.5 months and hes been spitting up quite frequently since we change formula milk to enfamil pro A+. Spit after feed, during burping, hrs after feed. Tried to change feeding position and give him lesser milk from his usual 100ml to 80 ml but it is still the same. He started with NAN opti pro ( constipate + phlegm) thn change to frisolac ( runny stool), currently on enfamil pro (more spit up then previous 2 formula milk). Im using dr brown milk bottle as well. Is it because its too thin? Not sure if i should change formula again. #pleasehelp