Hi, I'm A Male In My Late 30's.I Am Concerned

Hi, i'm a male in my late 30's.I am concerned about this clear to yellowish discharge with irritation and troubles urinating completely that I have been getting from my penis it feels strenuous at times.When I wake up in the morning there are darker yellowish spots all over on my underwear & discharge before I urinate.I have already went to the doctor for this, and was prescribed antibiotics azithro 1 dose & suprax 1dose.Already completed this medication & the doctor had tested me after I took the meds that came out negative.But I still have the symptoms yellowish stains on the underwear still with the irritation also.What can I do from here?