My suggestion is to go and have that check up, an ultrasound and a swab, or a urine culture, it sounds very much as a bacterial infection and that is no laughing matter.So convince your parents and go to a doctor...
Dave, if you were sexually active, you need to go and test for bacterial infections, and be completely honest about it because there are some serious consequences cased by some bacteria that is transferred sexually(oral sex included).
Now your can't pee problem: there is no urine, or you have the urge, and you can't expel the urine? Weak flow, inability to start the flow?