They are a phenomenon which I have experienced since I was very young. They occur infrequently, but often times when I am very sick. Occasionally, however they can be felt at other random times when my health is fine. When I was younger I remember hearing faint voices accompanying them, but seldom does this happen anymore.
I cannot see them. I cannot touch them. I can only feel them. I don’t know what they are and the best way I can describe them is as dense spheres that continuously expand and contract. They can be a bit unsettling, but also oddly comforting.