Car brakes on its own when starting to drive and slip, VDC and brake lights come on

I have the car listed above coupe, and every so often when I start my car and get to about 10 mph, the car will brake on its own for a split second, go back to normal for a second, then brake for a split second, and so on until I come to a stop. It also makes a loud noise whenever it brakes as well. When it does this the slip, VDC, and Brake light will flash and then stay on. When I start driving again after I have come to a stop, the car runs fine for the rest of my drive.
A note about the Brake light, it used to be the ABS light that came on in addition to the slip and VDC light instead of the Brake light, but I unplugged the white and brown sensors by the brake and then unscrewed the black brake light switch and then put everything back in. After that, the slip and VDC lights still came on but this time the brake light came up instead of the ABS light. It still did the same braking thing though.
I've also checked the brake fluid as well as all the brake pads and rotors and they all look good and have plenty of life left on them. I took the brake pads off and put them back on as well.
This problem also did not start until right after I got my car back from the mechanic after they replaced my u-joint. So they must've done something to make it do this.