Hi! The Last 3 Days I've Been Having A Feeling

Hi! The last 3 days I've been having a feeling of pressure build up in my head. It doesn't really hurt just pressure. What could it be? And also I've been wondering for a few years should I get tested for ADHD. I'm in college and I sit there and listen but not really hearing what's being taught. I also have issues trying to sleep because my brain just keeps going even when I'm extremely sleepy