My girlfriend, and I are sexually active. And I have noticed that even though she is well lubricated. That her juices and mine, create a burning sensation on the outside of my penis. This does not occur every time, but more times then I care to feel,. Is this due to her ph balance not being in sync with mine? What can we do to stop this painful for me problem? There is no pain on the inside of my penis, and it usually only occurs after we have both enjoyed a nice wet interlude.