Chronic UTIs

I get UTIs pretty often (once a month) and have recently had a couple yeast infections. My doctor said that probiotics can help. Does anyone have any recommendations for certain brands of probiotics? Or know or any other methods to prevent UTIs/yeast infections?
ps I always pee after sex and I don't use Summer's <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">eve</a> or any other type of irritating cleanser