The smell and smoke point to ballast failure so no worries about mercury.

Turn it off immediately due to fire hazard. That heat is the 15A circuit trying to short-circuit ... the heat is cause to get excited. A nice thing about incandescent bulbs is that all failures in the bulb lead to an open circuit - it safes itself. That's not so with a CFL.

The smell is probably a fried capacitor in the ballast and nothing to do with what's in the glass.

Once cool remove it carefully so as not to break the glass.

Unfortunately people want CFL's to cost about what incandescent bulbs cost even though there is a lot more to a CFL. The ballast is what gets cost-reduced past the point of reliability.

Panasonic sells some CFLs that are rated for use in enclosures but unless explicitly marked (and priced) for that a CFL must be used in a way that keeps both the base and bulb from overheating (if the glass part gets too hot the bulb gets dimmer earlier in its life). Inverted use should be OK as long as the heat from the bulb can escape past the base.