You should treat any new of unusual smells as potentialy deadly in a small space like a camper.
The active ingrediant in nail polish remover is Acetone, very strong chemical oder to it. It's used as a thinner and cleaner for some resins.
Acetone will make you "high" before it makes you passout. High concentrations can lead to brain damage and death.
If it's a barn yard smell, that's the ammonia that Aaron is pointing to.
Have you had anyone working on the camper lately, an acetone soaked rag could be the culprit.
When I was a kid I was going nowhere fast, now I'm an old man I'm going everywhere slow.