I've had a terrible headache all day. It wasn't that bad this morning, but after I got out of the shower, I noticed it was starting to hurt. Typing this up is making me wince, and slowing down my typing. It only seems to kick in when I'm doing something that requires muscle work, the more strenuous the activity, the more painful. At work today, I was lifting up an over-flowing box of papers (weighing about maybe twenty pounds), and I could barely move after I set it down. I took some Tylenol about an hour ago, but it doesn't seem to be working. Any advice on what it is or how to get rid of it?