STDs :: Burning Sensation While Urinating And Thick Discharge

i have had this problem for well over a year now after i had a one night stand with a girl. a couple of days after intercourse i noticed a thick cloudy yellowish discharge after urination. i would urinate and pull my pants up thinking i was done then i would feel irritation inside my penis like i had to go again but it even feels like something thick coming through. it doesn't happen every single time but i noticed my urine starting to look very cloudy at times as well. i have a slight burning sensation while i urinate. occasionally after the thick discharge comes out my testicles start to hurt for a while as well but this doesn't happen all the time. i have been back and forth to the doctors, first had a one off dose for chlamydia but no tests were taken and this didn't clear up the problem. i went back and had a urine test done and got given further treatment for chlamydia even though the tests came back negative for both chlamydia and gonorrhea. i didn't finish the second treatment for chlamydia but the symptoms still persisted. i went back once again and got tested for hiv, chlamydia and gonorrhea once again through a swab test and another urine test, all tests came back negative once again but my doctor decided to give me a shot to treat gonorrhea, (cant remember the name of it), which is supposed to kill all bacteria for that disease. that was the last i had been tested and treated for any STD but the symptoms still persist. i was fairly confident that it was either chlamydia or gonorrhea but with all tests coming back negative and no treatment helping, i am starting to worry that this will never be sorted and i will never be cured. i have a partner but i am too scared to even have sex with protection, this is how much it is affecting me.