Lump on back of head

I found today a lump on the back of my head on the right side. It's really really tender and about the size of the end of your pinky. It's on the right side under my hair. People say it looks like a bite. It's hard when you press on it (which really hurts). No one every remembers me hitting my head. I have felt weird feelings all around kind of where my hair is and in my jaw and I sometimes hear high pitched sounds the feelings don't hurt at all.
Please help me! I'm freaking out.