I am scared out of my mind of something, but I don't even know what it is?

My mind is in chaos, my heartbeat is rapid, my body is shaking violently, specifically my hands. Typing this without typos wasn't easy. I am currently so frightened of something I don't even want to consider the possibility of leaving my bed. I have no ******* idea what I am so afraid of. How can I find out what is scaring me like this?