I have this issue for about a week now. on the lower right of my head the back side, it hurts to apply any sense of pressure so sleeping has become a hassle. I hadn t hit my head so there wouldn t be any reason for this. Im not 100% if its a knot or not because to me it feels like my skull but I could be wrong, not sure. I have had an MRI not to long ago, both versions with the dye and without, this was for my constant headaches, they didn t find anything. I may also have a thyroid issue but these are on going issues that I am getting checked on. I do plan to go to the doctor if it doesn t go away in a few days because to be honest its freaking the f*** out of me. Never had any issue like this, and I have done research online and came up empty.. anything helpful would be great..