Alamak, mama relax sikit, kalau doctor dah check and lungs okay, tu dah good sign! Bunyi tu biasa je lagi especially at 3 bulan, congestion je yang nampak scary but it passes. A few of my mum friends pun pernah panic sama benda, tapi after nebulizer a few times and time, the sound goes away on its own. Jangan lupa maintain humidity, buatkan steam room simple-simple while bathing, and keep feeding as normal, that helps clearance. But if bunyi jadi worse atau dia struggle to breathe, follow your gut dan go back to doc, okay?