What's wrong with my car?

I have a 1995 Buick LeSabre with 160,000 miles. Today the engine started to give off a smell as I was driving and I checked only to find that the reservoir was almost empty. I filled it with coolant and that got rid of the smell but then I checked the oil when I got home and there was no oil on the dipstick, meaning that the oil must be low even though I just got it changed less than two months ago. Additionally, the engine seems to lack power and it takes forever to get it to accelerate when I want to go faster. I thought it was a bad head gasket, but usually the oil the water mix when that's the case and I haven't seen any oil in the water or vice versa. Help!