Two days ago, I was driving, my antifreeze came out the overflow valve, because my car almost overheated, the temp went to normal to hot in 30 seconds and i pulled over and turned it off. I got my thermostat changed and fluid changed. It runs ok, but my temp is going all the way to the L in normal, and before it stayed under the C the whole time, until i pushed it over 3k. I get no heat in my car, nothing is leaking, and the heads and everthing look ok. Please Help.