I also get overwhelmed by sensory overload. I feel like I am in the cockpit of a robot when it happens. It's like looking out of a window trying to make the controls of the robot work correctly. It happened recently when I was trying to read a menu. It was just mashed up letters that didn't make any sense. When this happens I try to take a deep breath and focus on one color. I look for, let's say, something blue. I focus on it for a few minutes. When I feel overloaded the stress of it happening can compound the issue. My color focusing is just a way to try and reset. It also works with touch. I carry a bag of trinkets that are fuzzy, squishy, smooth, etc. If I can shift my focus to the comfort item it kind of grounds the overwhelm.
I make myself crazy overanalyzing my symptoms too. I hope it helps to know you are not alone.