Sounds like cystitis. Drink a ton of cranberry juice and water, to help flush it out of your system, and hold on for as long as you can between restroom breaks to dilute it as much as possible (that helps ease the pain when urinating). If it's not cleared up in a couple days of that, you should go to your GP. They check your urine to confirm cystitis, and usually just prescribe a mild antibiotic to kill the infection.
You can get it from all kinds of things;
a thong/g-string underwear (allows bacteria to travel from back to the front),
using certain products in that area (deodorants etc contain chemicals that irritate),
It's nothing much to worry about, and you don't sound like you have too bad a case. Hope you feel better soon!
(I once had it so severe it felt like burning needles were being pushed into my urethra and even strong codeine-based pain meds were not taking the pain away!)