A few things come to mind especially when you said you were pulling a trailor 1)your pads glazed over 2)brake fluid needs changing, brake fluid absorbs water over time and boiling point decreases 3)you heated up brakes so much the fluid started boiling. Flush your system and replace with DOT 3 and better yet DOT 4 fluid. Don't know how heavy your trailor was/is but it probably over exerted your brake system. Thats why bigger heavier trailors have their own brakes because the brake system alone on the tow vehicle is not designed to take the extra force.