Thanks for your time. This is really alarming. Over the last month or so my penis swells (or balloons) after I have sex or masturbate. The swelling goes down by the next day, but it balloons up pretty big. It happens on the shaft under the glans. I am 27 years old and married. I've been tested for STDs (none) and have only been with my wife. The swelling is not hard, but soft and is not the entire penis but on part of the upper shaft. No pain whatsoever. Now I know the penis typically swells after erection, but not like this. It balloons out. It goes away the next day, but this is just really bothersome. Any idea of what this could be. Anything serious? Thank you.