I am not sure why you are having this discomfort. This is not usually something that follows the use of Viagra. Maybe you were more active during sexual intercourse than usual or had more episodes in this two day period and caused some mild local trauma. What you describe about your penile anatomy does not sound abnormal.
I think that you should leave you penis at rest for another week (no sexual intercourse, no masturbating) and see how the pain progresses. If it resolves, I think that you'll be fine. If it persists, then see a urologist.
This information is provided for general medical educational purposes only. It
does not necessarily reflect the opinions of Henry Ford Hospital or the
Vattikuti Urologic Institute. Please consult your physician for diagnostic
and treatment options pertaining to your specific medical condition