Ay sis, normal lang yan lalo na kung breastfed pa, ang breast milk babies usually poop ng frequent, sometimes after each feed pa! But since nag-mix kayo ng formula, it's possible na hindi hiyang talaga, kaya best i-check mo na with your pedia para sure, especially since may slight fever din, para ma-rule out kung may infection or lactose sensitivity lang. One of my mum friends had the same worry, at yung baby niya din ay nagbabago ng poop habit pagdating ng formula adjustment, pero the fever part kailangan talagang ma-check, love. Ingat sa inyo!