Hey! I understand what you could be going through, but since you are not aware about the root cause, I would suggest you to declutter your mind. To declutter your mind, right down the thoughts that are bothering you, and acknowledge it. Also, whenever you feel low, go out for a walk, talk to your friends to whom you can tell what you are honestly feeling. Most importantly, keep yourself busy in whichever way possible. Keep small goal, and try to drive yourself to complete and achieve those goals.