So I had very slight PCS with symptoms that were pretty much gone. My initial concussion was mild. About 4 days ago I felt extremely good, as if all my symptoms were gone. Then randomly, I pick up my pillow from one of the ends, and the other end seems to hit me right in my head. I'm thinking nothing is going to happen at all, but some symptoms seem to return (nausea and my emotions feeling weak and scattered) , as well as some soreness on the side of my head. The soreness goes away after 2 days, and 2 days later I am still left with symptoms of nausea and my emotions feeling weak. How and why is this happening? Is it something serious? Thanks