Poop of my baby

Good day , Just wanna ask my baby's poop is like paste type moss green color. what does it mean??and also he is constipated. every other po ang bowel nya. 3 months na po si baby. nagumpisa lang po nung 2months nya dhil ng intake sya ng antibiotic sa halak nya. fomula milk po si baby. Sana po matulungan nyo ako. salamat in advance po.