The car i bought 3 days is now overheating :(

[SellmeyourDVD]

Not very happy..... It started overheating so I turned the car off immediately, I sat for 30 seconds started the car back up and voila, cars' temperature is fine again. After I leave school later that night and almost get it home the car starts blowing ice cold air (even though i have it on hot) and it starts to overheat again. I pull over, sit for 30 seconds, and then the temp is back to normal and the car is not overheating. I just drove the car to work ( I had no other way to get to work, so I chanced it) and it drove fine the whole way here but my "hot" air is blowing ice cold still....

Anyone know what this could be? Radiator? Thermostat? Water pump? Do i just not have enough damn coolant in the car?

It's a 99 camaro with only 70k miles on it, carfax reported it has only 1 owner and never been into an accident