Is there something wrong with me?

I'm 21 years old and I'm always exhausted, no matter how much sleep I get. I get worn out easily from any physical thing, I have like no endurance towards physical things. I'm not in the best shape, but I am kind of skinny. Not anywhere near fat enough where I should get that tired that easily. I also get headaches a lot. I love basic math, and I'm decent at it. But after just a couple minutes of basic multiplication I get a headache and its hard to want to keep doing it.