Sudden decrease of milk consumption

Hi mga Mamsh! Ask ko lang kasi bigla bumaba milk consumption ng baby ko, from 3oz to 2pz every feeding. Kaka-1month pa lang niya last april 5, and napa-vomit siya 2x na this day. Mama ko kasi pag iniiwan ko sa kanya kada iyak ay pinapadede agad. Haays. Is this a sign of overfeeding?