It is probably some infections. If your doctor said you don't have to take any medicine, it is better follow his/her instruction. Drink more water and try not to hold your urine for too long. Some people are too busy at work and don't go to toilet even when they really want to. After a while, the toxic in the urine may do damage to your body and cause infection. Besides for women, after you have your bowl movement, it is better to wipe yourself from front to back instead of from back to front. It can minimize the chance of getting the bacteria from your bottom.