my boyfriend complains of dull pain from penis and feels like he is dishcarging but isn't?

Me and my boyfriend broke up for a few months then recently had a night of passion. I messed around once, with protection with another guy. He had sex, protected and unprotected sex w/ a girlfriend for 2 months. I've been nonactive for 3 months and him he says for 1 month. Two days after we had sex, he complained about having dull pains from his penis and feeling like his penis has to discharge something, but isn't. there is no redness or rash. No bleeding. Has dull pains all day and sharp pains when it is erected. I think he pulled a muscle in his penis. But what could it be?