TMI: Question about discharge/irritation?

Just wondering if any others are dealing with this issue? I'm having a moderate amount of vaginal discharge, which has been the same for several weeks now -- about 2 months. It's thin and watery and honestly looks exactly like milk. No odor, no chunks, nothing gross. The problem is, it dries on my labia and gets REALLY itchy and obnoxious, and even builds up a white film which gets underneath my hood and in the folds and requires cleaning with a Q-tip. The itching gets so bad that the tissue swells and tears. I've never in my life had anything like this, not even with my previous pregnancies. I've done several yeast infection treatments as well as 3 rounds of Metronidazole, and nothing is helping. OB is clueless as to what else it could be. I also tried Rephresh and eating yogurt to see if it was a pH issue, neither helped. I'm getting really fed up with having to wash every time I use the bathroom in order to keep it off my skin, as that in itself makes things raw as well. Any ideas?