Ay buti na lang na nakita mo agad ang signs ng teething, pero honestly ang diarrhea plus the formula change is confusing talaga, kaya best to check with your pedia ulit para ma-rule out kung bacterial or viral ito, or if it's really just the formula adjustment lang. Most of my mum friends had to try a few formulas before one worked, at sometimes it takes 3-5 days pa lang para ma-adjust ang tummy ng baby, pero 4x a day of loose yellow poop is worth getting checked especially with the teething happening at the same time. In the meantime, make sure siya hydrated well, offer water, coconut juice, whatever she'll take, at bangga nyo ng maigi ang areas na exposed sa diaper dahil mabilis ma-irritate. Sending you strength, first time mom life is chaotic pero kaya mo yan!