exhausted! 10dpo

I'm 10dpo and for the last 3/4 days I've been ridiculously exhausted. I'll get up and be awake for all of 2 hours before needing to go for a nap which can last anything from an hour to 6+ hours. Even after my longest naps I've been tired pretty soon after waking up. Could this be a positive sign or more likely something I should see a doctor about (eg iron/vitamin deficiency)