The skin on the left side of the urethra opening of my penis has been irritated and and red for the last 6 months. Been hoping it was just an allergic reaction or something that would go away but it recently started slightly swelling only on the red irritated side of my penis head around the affected side of the urethra opening. There is no pain or discharge or burning or bumps, just some sensitivity and irritation when it rubs against fabric. I'm circumcised and never had unprotected sex though i did have unprotected oral sex performed on me a few months ago, around the first time i started noticing the symptoms. Is this potentially a serious std or something less serious?