You're losing coolant, (bigtime, from the sound of it) which should never happen. You've already let your car get MUCH too hot if you drove it home smoking. Get it fixed ASAP, or you're going to be spending money on a new car instead of a new cooling system.
Overheating could be one of a few things. A clog which is unlikely since it just popped up suddenly. A bad thermostat can get stuck shut and not allow coolant to flow, a bad water pump but with a bad water pump you should see antifreeze leaking near pump, or a headgasket, if headgasket I leaking that's gonna be the worst scenario.