I have suffered from yeast infections for almost all my life, (am 31 now). I found that I would get only 2 days relief from messy cream medications and oral Diflucan. I finally saw a great OB/GYN who immediately started me on Boric acid suppositories. So, I take (vaginally) two capsules a week, dose is 500 mg. Since starting I feel incredible and do not have any more problems. You can buy Boric acid OTC and make your own pills or go to a compounding pharmacy and they will make the pills for you.
Also, whoever posted to put honey on the external vulva: that is a really really bad idea since yeast thrives on sugar. Please do not follow that advice.