8 Month Old and Projectile Vomit PLEASE READ!!!!?

My son will be 8 months old on the 15th! He has NEVER had a problem with vomiting or spitting up! He has vomited 1 time and he was like 3 weeks old. I just feed him his bed time bottle, 8oz like usual. He actually only ate 7oz and was asleep. He started to move, like he had to burp or something? So I I set him up right (like you do when your burp babies) and went to burp him. He vomited his WHOLE bottle!!! This has never happened before, so I am not sure what is wrong? He is formula fed, so it is not something I had to eat. We both do have a cold, but nothing huge...no temps. He is in his crib right now, so I can settle down.......FREAKED ME OUT BIG TIME!! He is wide awake now! I am wondering, how long before I make him another bottle? He vomited everything up, so I am sure his lil tummy is empty? What could have caused him to vomit in such a way?