if it is a head gasket wouldnt the car run poorly? or what exactly should i be looking for

Things to confirm blown head gasket ... Check the oil dip stick if the oil looks milky there's antifreeze in it which means blown gasket ... Check the antifreeze reservoir see if there's oil floating around in there ... Check for white smoke at the exhaust and smell to see if it smells sweet ... It could also be a cracked head ... Did you have over heating issues? And if you did anything with the cooling system ? Make sure to bleed it and get the air out to avoid vapor lock

Have you replaced the thermostat? Does it cool down when you turn of the heat ?

The most common cause of overheating is low coolant level or air trapped in the system. If you have some sort of leak your coolant level may be so low it won't cool properly. Fill it up and see what happens. If the coolant gets low again soon you have a leak somewhere. It may be leaking into the engine and being burned off. If it happens gradually enough you won't notice it. My car does that. It may also show up in the oil as has been mentioned or it may be leaking externally through a gasket or even a leaky radiator. There are usually tell tale signs of this under the hood. As Nique said it is also very important to bleed all air from the system when refilling it if it has been drained for any reason. There is a bleeder valve near the thermostat for that. If there is air in the system it will overheat even though the system appears to be full.