Aww mama, please do bring baby to the clinic or hospital today, at 20 days old, any breathing changes or congestion needs to be checked by the doctor right away, okay? Don't wait. A few of us mums have gone through this worry, and the doctors always say better to check early with newborns. Could be just mucus buildup or something more, but only the doctor can tell. Jangan worry lah, but do go quickly, ya. Wishing your little one feels better soon!