Hi, I had almost exactly the same issue over a few weeks at the end of last year (when I was going through some hormonal readjustment returning to menstrual cycle after about 8 months without one-since stopped the pill). It now seems to have passed. I know I do have an intestinal candida problem which I'm researching into getting getter from. When I got this problem (it's almost the consistency of water isn't it?!) I assumed that it had progressed into a yeast infection and I do went to the gynaecologist to be told that it was ultra healthy and I had nothing to worry about. I'm in my 30s, have never had a discharge like that before, and know that I am NOT ultra healthy! So, I know what you mean, is it yeast or not? I think very possibly but a fortunate form (in that there's no real discomfort).
For the intestinal candida problem, I am currently trying homeopathy. In looking up a bit about homeopathy on the internet, I happened to come across different remedies for different types of yeast infections--one described this kind of discharge.
Perhaps you could try a probiotic pessary to see if it's just a case of reintroducing some good bacteria. Have you ever tried an anti-fungal pessary (though resort to that second--i'm less and less a fan of drugs!). If it doesn't clear up, you could do some tests to find any causative factors. Do you think you have intestinal candida (do you get any gastroenterological symptoms when you eat sugary foods? etc) or the discharge as a lone symptom?