Alamak, that's quite uncommon at that age lah, honestly I haven't come across it among my mum friends either, kena check with the doctor first to make sure what it is, because sometimes anak-anak punya symptoms boleh misleading gitu. Once you know for sure what's happening, the doctor can advise on treatment, whether it's just diet adjustment (more fiber, more water), or something else that needs proper care since he's so little lagi.