Why does out heater suddenly have a strong lighter fluid smell?

We have propane heaters in our house. The heater in our hall just recently started smelling really bad. Like lighter fluid or something similar. It's been smelling odd for a few weeks now. But just tonight it REALLY smells bad. We even had to turn it off because it was making us all feel sick. We were putting off calling a gas man out here because of not having money. But it looks like we may have no choice. I heard carbon monoxide is odorless. But that smell can't be anything good.