I had this problem with my old corsa, It was the cam or the follower was chipped or somethin like that, wasnt releasin harmful fumes quick enough. Maybe scooby the car genius might be able to clear it up?
The oil filter had also callopsed so check that out. Check that out coz if its that you wanna catch it quick before it knackers your engine up!
The first things I would do if it happened to me again would be check oil filter, air filter and fuel pump.