Hi doc. there is discomfort on my penis. more specifically, the opening of the urethra. this started this morning. i had oral sex 1.5 weeks ago?

STD check: I suspect you already know the answer to this question. You need to get an STD check. A probable cause is a herpes infection. Please see your Dr or a sexual health clinic. The only way to protect yourself is to wear a condom.

Needs check: Will need a check for STDs as the others have pointed out. To make it less embarrasing some clinics can offer a urine test for some of the infections, however will need a careful further history as may need to be examined/have other tests done depending on your situation. Please see your doctor or sexual health clinic, and use protection/abstain until you know results