What's the difference between normal possetting/stomach bug/trapped wind in young BF baby?

[Sidewaystrolley]

DS is 12 weeks. Over last 24 hours he has been off his feeds (BF-ing) and when he has been feeding he's been doing big possets, sometimes the whole feed is coming up, but just out of the side of his mouth, not in a retching way.

He's also been crying a lot more, I think, due to wind. We've had some big burps but they don't seem to make him hungrier. He is also sleeping loads. Has no temperature.

[rabbitmummy]

Teething?!