My engine temperature is fluctuating into the.

My engine temperature is fluctuating into the red then back down again! I added fluid and started the motor, the temperature then went into the red again then started fluctuating again, then to low coolant level light came on again. I want add more fluid but I have to wait for it to cool again. My thoughts are either I have a stuck thermostat, an airlock, or a blown head gasket, but no real signs of that in the oil or exhaust, yet that is? I wanted to have a carbon monoxide test today but all the mechanics in town were busy as heck! Any input would help please! I hope it's just an air lock and I just have to wait for it to cool and add more fluid since the low level light came back on, not sure about it though so I thought that I would look online for more input. Thanks, Kevin PS the radiator hose felt like it had good pressure when it got hot and the fans came on! I wish that the damn thermostat wasn't buried by the Throttle body so that I could replace it easier!