How long has this been going on? You're sure it's a 'he'? How old is he ?
Over the counter/pet store ‘wet tail' treatments are often just solutions for diarrhea. It may be attempted, but if not cleared up relatively quickly, vet attention is probably going to be needed urgently.
Wet tail doesn't always present with obvious feces; sometimes it's a whitish, infected looking discharge. When you see this, there's no point in trying to treat diarrhea - it's important to see a vet pretty quickly (same day if possible).
There's more info about it here http://www.peteducation.com/article.cfm?cls=18&cat=1799&articleid=622
It sounds like you're catching this early - which is very promising. Many cases aren't treated until much further advanced and the hammy goes off food, becomes lethargic and symptoms are undeniable.
I had a feeling it was a she - it would still be important to have her seen. It's probably not so much an intestinal infection as a 'female' related problem; however, depending on the source (bacteria, fungal, etc) it may get worse, quickly spreading.
If she's been exposed to a male within the last two weeks or so, this may be Dystocia (babies stuck inside) - and it's an emergency situation.
In any case - there's no way around it, she needs medical intervention. With another two years or more expected in her lifespan, it's certainly worth the care to help insure her chances.
http://www.hamsterhideout.com/hamsterbasics.html This link is terrific for hammy families!
Good luck with her - and let me know how it goes ok?