Depersonalization?

yup, It sounds to me like anxiety. I used to get it, i call it out of your body experience. It feels really scary, but once you realize that its nothing it goes away. The first time i got it, i thought i was gonna die. I FLIPPED OUT. But its was just anxiety and i always expect to get it but then if it happens it is just uncomfortable but not dangerous, just keep thinking that to yourself. Just to make sure thats what it is you should go to the doctor and get a blood test. It doesn't seem dangerous how you are describing it.