Hi , My Baby Is 37 Days Old , Bottle

Hi , my baby is 37 days old , bottle fed with Nan 1, taking 90ml every three hours , two days ago he started spilling milk out while feeding and not even taking 30 ml before sleeping for around two hours, once awake , he repeats the same thing he is not spitting out after he finishes but spilling during nursing
Any advise? What could be the reason ?
Thanks