For a few days now I have experienced leg weakness and arm weakness, and I constantly feel fatigued and tired. I am dizzy and lightheaded all day everyday, no matter how I treat it, it doesn't subside. My eyes feel slightly strained and unusually I have had muscle twitches. I feel some sort of pressure at the back of my head, and I'm experiencing some sort of pain on either sides of my head. I feel quite nauseous but I haven't vomited yet. If I lift my head up or down it makes me extremely dizzy. I've been very scared that it might be a brain tumor. Any ideas or similar experiences?