Slowly Changing Formula Milk

Hi all momma bear🐻 now my son is 2yrs old and 5months. Since NB till today my son been taking from Enfalac baby to Enfagrow Step 3 in original flavour. But lately ni, dia kerap cirit birit so after consult with doctor we plan to slowly tukar formula milk dia. Is there any suggestions what formula milk yang elok for try and error part? Thank you to all momma bear🐻💗🍼#plshelp