Problem with negitive numbers

[EHaskins]

I've been working on a velocity PID for motor control, but I'm having trouble.

When the PID calculation returns a positive value the code runs fine, but when it return a negitice value the motor output begins jumping appearently randomly from very high(5 digit) to very low(-5 digit) values.

Once this happens the PID reacts correctly, but due to the values that a far outside of normal it never recovers.

Here is the code I think contains the issue, but I can't find it. I added some comments to help explain the issue.

void MotorControl (unsigned char motor)
{
         
    //The printfs in CalculateSpeed() give correct data. 

	int speed = CalculateSpeed(motor);
	int output;
	//printf("speed on motor %d = %d\r\n", motor);
	//printf("Speed Goal = %d\r\n", speedGoal[motor]);

    // Last line in PID prints the PID output, and it always appears correctly. 

	output = PID(speed, speedGoal[motor], &pidInfo[motor]);
 	currentOutput[motor] += output;

	if (loopCount == 0)
	{
          //This is where the issue is obvious. It prints strange values within
          //the same loop as PID() returns a negitive value, and then until reset.

        
		printf("Output %d = %d\r\n\r\n\r\n", motor, (int)currentOutput[motor]);
	}
	switch (motor)
	{
		case 0:
			MOTOR_ONE = LimitInput(currentOutput[motor] + 127, 0, 255);
			//printf("Motor one set during %d\r\n", motor);
			break;
		case 1:
			MOTOR_TWO = LimitInput(currentOutput[motor] + 127, 0, 255);
			//printf("Motor one set during %d\r\n", motor);
			break;
	}
}