Any help would be appreciated

I've posted about this multiple times but the issue still persist.... Ever since I've been treated for Chlamydia I've been having this weird sensation (not really and itch or pain) inside the head of my penis a little below the opening. Its been going on for the entire year so far (I got chlamydia last year October and was treated in November and the sensation started around the time I finished my first treatment)... I've done multiple test since then and doctors have assured me that I have no STD or STI (took my last test in July and haven't had sex since...still nothing)... I've went to Dermatology to see if its a skin thing and no luck... I've gotten a Cystoscopy and no luck.... I even recently went to the hospital and the doctor said "Its most likely being caused by stress and is all in your head." But the thing is the feeling is very much real and I don't want to debate with a professional in their field of expertise but it doesn't feel like something thats being caused by me stressing (which I don't do a lot of, and when stressed the feeling doesn't occur)...The "sensation" last no more than 3 seconds and happens at least once a day (sometimes more). I know my doctors said I'm clean but I fear one day upon trying to have a child or have unprotected sex I may pass something unknowingly unto my partner...... and that'd destroy me..... Its not an issue with my hygiene, detergent or soap, I've changed them multiple times, I've used treatments for yeast infections because I thought it might be that and still no luck.... Right now I'm out of options and just looking for suggestions on what it could possibly be. Hopefully someone can help. Also heres a fourm I found with people experiencing the exact same thing but some of them I belive have an STD/STI, I on the other hand don't (according to my doctors) - http://www.ourhealth.com/conditions/sexual-conditions/tingling-at-the-end-of-penis?p=4

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