Strange brakes

[7.3'00]

My brakes recently started making strange noises. Whenever I'm going at low speeds there is a very loud squeaking noise coming from the rear end of the truck. I crawled under there but couldn't find anything out of the normal. And when I push on the brakes going the low speeds it makes that really loud squeaking noise. I know that the brake pads are not dusty because this a completely different sound. Also whenever I have been driving for a while, my brakes are HOT. I sprayed them down once and there was steam coming from them. Lastly there is a black grime covering all of my rims.

Thanks