All Day Long, I Can Feel My Heart Beat Faster

All day long, I can feel my heart beat faster than usual. I didn't feel sick, but I knew because I can feel it beat faster, and it keeps on growing more uncomfortable. I haven't had coffee in weeks. During around 12:50-2:20 I got a headache and I started getting really warm. But I didn't feel sick besides the massive headache. I don't know what to do, I'm really scared. I'm only 16 by the way.