What are some causes of a slight headache that lasts for 4 days?

What are some causes of a slight headache that lasts for 4 days?
I’ve been having this very slight headache for the past 4 days, i am wondering what could the causes be for this. And also can STD’s or UTI’s cause this?

There are losts of good answers, but the best answer:

Answer by Frankenstein’s Punguin
Any chronic pain related to your head may be serious. You should see a doctor instead of asking us.

There are just too many possibilities.

Add your own answer in the comments!