What is causing these symptoms?

A few days ago I decided I needed to start drinking more water, so I drunk more water! Ever since then I've been having a dull headache. (it could be a tension headache but idk) Yesterday I started having heart burn (I've never even had that before). And I've also been peeing and doing the number 2 alot (or aka pooing) :) my urine is clear btw! Does anyone know what could possibly be causing these symptoms? I'm 17 years old, I'm a girl, I had my period last week, I don't drink alcohol or do drugs or any of that! I've kind of been stressing over college alot though but not too much! Idk if that could be the cause because I'm not majorly stressing! But yea THANKS in advance!