Aiyooo, ini boleh jadi growth spurt atau dia tengah teething early (kadang-kadang ada baby yang start teething at 3 months, even though jarang). A few of my mum friends went through this jugak, baby suddenly kurang minat susu for a few days then balik normal. Since your baby is aktif dan ceria, it's likely okay, but definitely check with your paediatrician to rule out anything else macam tongue tie or infection, especially if this lasts more than a few days. In the meantime, jangan paksa, tapi keep offering regularly, dia akan minum bila dia siap, and sometimes babies get distracted at this age je.