ive had this problem for over 6 months now, ive been tested 3 times for an std test and theyve always been negative,the symptoms, red knob,itch penis, sore testicles, penis feels like its burning and muscle ache especialy in the legs however i have never had a cold sore or any blisters on my penis, could it be genitial herpes
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If you were not tested for herpes then the tested would have showed negative. the routine std test usually doesn't cover herpes, it's one you have to ask to be done by telling the doctor you think you may have been exposed to herpes and tell them what symptoms you have had.
You should get a swab done while you have the symptoms it may not be herpes but, it does sound suspicious.
You can have mild out breaks of herpes that can feel like a rash. There doesn't always have to be big sores or blisters showing up.

If you have been tested 3 times but came back negative three times the chances of genital herpes is quite slim, this is because they test on a "cellular level" meaning the virus cant really hide that well when they test for it. Have you asked to be tested for various other std's? Syphilis, gonorrhea, chlamydia but these usually show the symptoms of discharge from the penis most of the time. I think really sit down with your doctor and see what else it could be..
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Student Nurse @ griffith university. this is only a little information written above, see a doctor/physician for medical care.