Can someone help me figure out what's happening to me so I can more accurately help myself out?

So normally I deal with a somewhat bad case of depression, but last night something just kinda snapped in me. I couldn't stop shaking and I felt really scared and anxious. I did eventually fall asleep, but when I woke up it was still there, and it's been going on and worsening throughout the entirety of today. I don't know what happened, I wasn't under any real pressure nor was I worried about anything in particular. It just kinda started and I've been shaking and breathing heavily and my mind won't stop racing and I feel like I'm going to explode mentally. I can't really tell honestly. It's just some horrid mental anguish thats stuck onto me randomly since last night and it's only worsening. Can someone please tell me what this is called or what's happening to me, so that I can find out how to help myself?