Formula milk hiyang or not

Nan optipro po milk ni baby ko, 3weeks old, mixfeed, napansin ko lang everytime na mag formula sya, naglulungad, fussy at hndi makapupu, tapos nag ggrunt din sya lagi parang may kabag, ibg sbhn ba nun d sya hiyang? And pwede ba magswitch ng milk without the consent of the pedia?