Hmm, 5 hari sekali tu memang agak lama untuk baby 2 bulan, apalagi kalau najis berlendir, sebaiknya check dengan doctor je untuk pastikan baby okay dan tidak ada constipation atau sensitivity terhadap formula. A few of my mum friends experienced similar when switching between breast milk and formula, and their pediatrician suggested making sure formula mixing ratio betul and baby getting enough water, plus sometimes kena adjust brand formula if memang tidak suit baby's tummy. Jangan worry la, tapi better safe than sorry dengan newborn!