I have been dry humping a lot with my girlfriend wit occasional semi penetration. Today whilst I was washing under my foreskin, I felt a sharp stinging pain. Upon carefuly examing my penis I found that I have a tiny red sore. What I need to understand is that could this be an STI? My girl and I have been faithful to each other I trust her a lot and I only see her. We are both HIV negative, we went for testing last Thursday. Please help,what could this sore mean. can I rule out the posibility of an sti. Other than seeing a doctor, what should I do because here doctors are the last resort, they are expensive.