I suddenly felt veryyyy overwhelmed emotionally and lost my balance and started sobbing, i couldnt see anything in front of me, and it happened for no reason. what is this and why did it happen?

Those are signs that there is something that's being ignored, something that's deeply affecting you but is not resolved yet. It is not something that happens in a moment, it is usually a long time cause. I have been there and getting back on track from such a situation is a process that takes time and patience.

Sometimes, there are things going on in our subconsciousness that we are not aware of because we have been suppressing it, or too busy to tap into how we are really feeling to see what needs fixing. After a while, there are a few things that can cause us to become emotionally overwhelmed by doing this; 1. Triggered by something we heard, saw or thought of, like memories. 2. We have reached our peak of how much we can suppress. 3. Something unrelated happened, which caused us to feel an emotion, whether anger, sadness, etc, which then cause us to lose focus on the numbness we have been using to cover up our real feelings.

Think about why it might have been triggered. Have you been very stressed lately? Or have you had any other issues with your health recently? Something that could have seemed like a simple thing so you might have brushed it off? Keep track on how you feel for the next couple of days. Pen down anything that bothers you physically or mentally. That might help you narrow down what happened. Try talking to someone you trust. Maybe they could help you. Stress or anxiety can sometimes cause this to happen. See if engaging in activities you enjoy and talking to someone makes you feel better.