Ay, ganyan talaga sometimes, baby's tummy can be sensitive sa formula changes, kaya parang reject lang agad! One of my mum friends had the same issue at nag-try sya ng different brands (like lactose-free or gentle formulas) bago ma-adjust baby niya, so maybe check with your pedia kung ano best option para sa 10-month-old mo, could be ang formula mismo, or maybe need mag-introduce ng other foods na mas filling na instead, like soft rice, viand, etc.