What could be wrong with my brain?

Since Monday, I've had trouble concentrating, speech problems, short term memory loss, vision problems,dizzy spells, I do things that I really don't want to do like stomp my feet for no reason, or i'll say random things. I'm forgetting vocabulary I want to say and I don't feel like if I'm the one saying or doing things. Like if I'm controlled. My thoughts are cloudy, and I feel like if I'm sleeping awake. I've had fatigue for no reason this whole week and I'm constantly yawning. I feel disoriented, confused, pretty much all of the above. I have this feeling of nothingness like if I'm sleeping awake. I've also had this pain that comes and goes and varies in intensity around my head. Sometimes the pain will be on the left side of my head, the back, the top or the right. The ophthalmologist didn't find anything wrong with my eyes, and the pediatric said it probably isn't a tumor because I had an MRI 5 years ago and it didn't find anything wrong. I'm only 15, I don't do drugs, and I don't drink. What could be the problem?