from what i've read it could be the thermostat or a blown head gasket. obviously i know these two things are very different. but since i don't know much about cars i wanted to get some other opinions before i put it in the shop or had someone change the thermostat, if it doesn't need to be done.

the heat went out in my car and about 3 days later it started overheating. at first it would go miles before it started getting hot but it gradually started heating up faster and faster. eventually it got so hot the engine started running poorly and loosing power.

i know one big sign of a blown head gasket is white smoke coming from the exhaust but i haven't experienced this.

anyone else know what it could be or dealing with the same issue?
any input would be greatly appreciated.