Normal je, mama! 4 bulan babies yang minum combination FM + BF memang boleh pop varying consistency depending on which feed dia dapat, BF poop usually softer and more frequent, FM poop bit thicker. As long as baby alert, gaining weight steady, and wet diapers okay, you're good. Kalau ada greenish colour, mucus, atau baby seems uncomfortable, then boleh tanya pediatrician just to be sure, tapi mix feeding babies' poop memang different jenis-jenis.