One week ago, I started developing a stinging sensation in my penis around the urethral opening and glans. I had masturbated and used a hair conditioner as a lubricant. After 3 days there was no relief so I went to the clinic. I was tested for STDs (no very sexually active but an occasional insertive oral sex episode and the most recent was 3+ weeks in the past). All test were negative as was the urinalysis for bacteria. I do not notice the stinging when I shower or sit on the toilet and often not when moving around. There is no discharge, sores or pain when urinating. I did try a yeast cream and a jock itch cream for a couple of days. I masturbated twice more this week and it's noticeably worse afterwards. It is also worse when I sit or when my penis rubs against my underwear. Could this be cause by the conditioner, too frequent masturbation, or something more major? The doctor I saw gave me no advice other than watchful waiting. I would not say it's worse over all, it just doesn't seem to be getting much better.