Projectile vomiting - when to worry?

[Samvet]

Hello,
I would appreciate advice from more experienced mummies. My 9m old has in the last week had 3 projectile vomits. 2 after nighttime milk and today after lunch at nursery. He had a cold 2 weeks ago and still sounds a little nasal and has a cough. He is also teething like crazy. All vomits have been after eating alot (he has a big appetite). He is otherwise well and no temp or diarrhoea.
My questions - can he just be overeating and his stomach says no more?
Could it be related to teething/bit of a cold?
Should I worry or just limit the size of his meals a bit?
Do babies always know when they have had enough?
thank you!

Hi, my DS def did not know when he'd had enough, as a newborn he used to breast feed til he was sick then start again. And was pretty much like this when weaned, i had to control what he ate else he'd eat til he was sick all the time. He was a chubby tot and is now a stick thin 6 yr old running round all the time but still with a healthy attitude, tho i'm not complaining cos he eats anything!