Have you ever cried without understanding the reason?

The title is the thing which is what I'm currently going through. I don't remember the last time I cried but rn I can't stop the tears coming down my eyes. I clearly don't know the reason, I'm alone in my hostel room and have a midsem exam the next morning I don't understand what the hell is going in my mind. I don't want to reach out to anyone like the way I'm rn. I was about to call my parents but I stopped myself as I'm living in a different state rn and I don't want to bother them.