katkatkattkac:
the servo is powered by my laptop as well, it's attached to a breadboard
Powering the servo from the Arduino's power supply is not recommended, although you can sometimes get away with it for small servos that are only lightly loaded. If the problem started when you increased the load on the servo it's quite likely you're just overloading the Arduino. You could try disconnecting the load from the servo and see whether it works OK when it can move freely - if the servo works OK like that it confirms that this is a power supply problem. The solution is to provide a separate power supply for the servo, for example a separate battery pack or regulated wall wart. The battery pack or wall wart power supply ground needs to be connected to the Arduino's ground.