My room smells like cabbage?Watch
And please, don't say cabbage.
Also buy a chair, laptops aren't designed to take the weight on a person on them.
Are you sure it's not the smell of what your flatmates cooked for dinner? Is your room near the kitchen? If the smell comes and goes it's probably food, even if it smells horrible lol.
A friend of mine once got hospitalised after a particularly bad incident with a leek. He's never been the same since.