I know this may sound a bit disgusting but just dab a finger down there and then have a sniff...if it smells a bit cheesy it may be a mild yeast infection, 5mm of cider vinegar in your douche will create the right PH for the bacteria you want. If it smells fishy, it's old lube, when I was using synthetic lube I douched after every dilation. Some people will tell you not to because you'll flush out all the good bacteria, but this is rubbish, 5mm of sea salt in your douche will not affect the bacteria you want while discouraging the ones you don't. If it smells like rotting meat it's an infection, you may have to use something like beterdine for a couple of days to kill everything off and then start again. If it smells fresh and salty it's just normal vaginal lube/discharge and is nothing to worry about. I get damp knickers all the time, usually when I'm skating (it's the road vibrations) and I've got slightly aroused. If I'm skating for an entire day I'll but a freshness liner in because it can cause chaffing, otherwise i don't bother.
You have to remember that natal vaginas are only self cleaning because once a month all that gloopy sticky blood comes out and takes all the nastiness with it. any woman who doesn't keep her vag clean will find it smells funky.
Also I've just moved to using coconut oil to dilate, it helps inhibit yeast growth, will be absorb by the body because it's natural so won't go off and smell fishy. You vag also smells like coconuts just after dilating. I've stopped douching since I started using coconut oil, but I wash own there once a day.
Also if you have thrush, you'd know about it...I've had it and it's horrible, a nasty burning itch and a thick white discharge.