What's wrong with my 1998 Dodge Ram 1500? Please help!

My dodge ram 1998 Dodge Ram 1500 with 95,000 miles. It was used by a friend to haul a
heavy load. A big trailer with a couple thousand pounds to be exact. Well, he was driving
on cruise control at about 65 for a couple hours and it started overheating and the engine
light came on and he pulled over. Antifreeze was sprayed all under the hood. Why did it do
this? Also, the truck was overheating. He stopped for a bit and kept going. The engine
light came on and he was able to drive the truck and everything back home without
reaching the red zone on the temp gauge. Now, the engine light is off. But when I drive
without a trailer, the truck still overheats. I'll stop at a stop light and when I accelerate, I
hear fluid moving in the dash and the truck starts cooling back down, then slowly starts
increasing again until the next time I hear that fluid sound. It's winter and the heat does't
work now after all of this.