Aww nakakagulat talaga when formula changes and suddenly baby gets upset stomach or digestive issues, pero honestly it's hard to say kung it's really the formula or something else na nangyari sa same time, a few of us mums namin din nag-switch ng formula at nahirapan ang babies namin initially. Best thing would be to check with your pedia first to rule out any infections or allergies, kasi sometimes babies' tummies are just sensitive sa timing ng pagbabago, pero if it's really the new formula causing problems, your doctor can help you decide kung babalik kayo sa old one or mag-try ng ibang brand na mas gentle sa baby's system. Hugs mama, alam ko ang stress!