3rd time white pus like urethral discharge, but no std?

Three times I have had bouts where I have a white pus-like discharge from the penis, accompanied by internal irritation. It happened at intervals of 2 1/2 years, then 7 months. All three times I, as well as my female partner have tested negative for all STDs. Ive never had an std before. I've been tested several times and examined by several doctors. The lastest being a urologist. The urologist said to try diflucan first to see if it is a yeast infection. If the symptoms persist, then take medication for possible trichomoniasis infection. If that didn't work then he would have to do a visual inspection with a camera scope. I took a test for trichomoniasis (urine NAA test) and that came back negative as well. My last 3 partners have also tested negative for all STDs, including trichomoniasis. I had a rather complete urinalysis done and the only thing found was a trace amount of leukocytes. During this last bout I noticed tiny, white, square shaped particles came out and within an hour the discharge turned clear and the irritation lessened dramatically, but was still present. The discharge quickly stopped altogether, except for a few times when a little bit would be evident, but would go away again. I was put on a 7 day regimen of diflucan and symptoms went away by day 6. The other two times this happened in the past I took the standard std regimen of the shot and the pill. All three times, the episodes have lasted approximately three weeks, then they go away. I have noticed a slight amount of clear moisture inside the urethra, which I think is normal. I have expressed a very tiny amount and it was clear and slightly thick, like the very after end of ejaculation that comes a minute or so later after semen is expelled. No sign of any color. No sign or internal irritation. I have had a few incidences of itching EXTERNALLY on the shaft of the penis and one time a very slight patch of something rubbed off that looked like a small amount of dried soap. The itching would come and go. This happened towards the end of the diflucan treatment. It felt a little sensitive, but has gotten better. What I want to know is if I am cleared for sex. The urologist said it was okay if symptoms go away, but I am very scared of there still being something there because this has happened three times now. Will condoms be enough protection? How long should I wait to confirm the symptoms are gone? It's been five days since I took the last diflucan pill and it feels and looks okay except for the slight, occasional itching on the underside shaft of the penis (about an inch or so down from the glans. I am circumsized, but it's right at the line where the foreskin would start). What should I do?!?