Are there unknown stis? urethritis symptoms after sex but negative for chlaymidia,gonhorrea,mycoplasma,ureaplasma,trichomonas,gardenella,herpes,syphilis,hiv. urine culture. doxycycline didnt help. urologist didnt know what to do? advise?

Not that we know of!: Urethritis is often causes by chemical irritation or friction. The urethra is so close to the vagina that it can be injured easily. Also, If urine is very concentrated from not drinking enough fluids, it can cause irritation to the bladder and urethra. Drinking fluids until the urine is very light is helpful, as well as sitting in a warm bath without soap.