I have had a mild paranasal sinus disease for 7 days now. I was prescribed augmentin 875 and I am taking that 2 times a day for the past 4 days now. I was also prescribed sudafed 4-6 hours that I have been taking for 2 days. Yesterday I started having trouble urinating and pain in my penis. I also had pain while ejaculating. This is still happening today. Do you think this is a side effect from the medicine or do I have a UTI or urethritis or something like that. I'm 18 years old and have never had these symptoms before. I had unprotected sex 2 1/2 weeks ago.