Try shoving a urinal mint in her vagina for about an hour, you can buy them at costco, or if you are broke, snag one from s public restroom...
When me and my first girlfriend decided to be sexually active, I couldn't give her oral without gagging because of the taste and smell. After awhile, I noticed it went away and started to taste like... well, nothing. I believe she just didn't wash down there much because it wasn't an "experienced" territory. We were like 15-16 though, so yeah. She may just need to actually wash it for once.