Ahhh 4 bulan tu memang masa dia start merengek lebih! A few of us dalam group tried different things, some say baby teething early jadi uncomfortable, tapi most of the time it's just them discovering suara baru and wanting more attention, tu je. My daughter kat age tu pun sama, merengek sikit-sikit, especially kalau dia tired or overstimulated. The best thing I found was just making sure she's not hungry, diaper clean, and maybe just carry her dekat-dekat sambil buat routine, sometimes they just need reassurance je. Try juga check if ada colic or reflux signs, tapi mostly at this age they're just figuring out how to communicate, so patience je mama!