Vagina question

*Please read* I'm fairly young so I'm sorry for possibly sounding uneducated about my body, but I've been horribly dry in that area for months now, and sex is really painful. I went to the doctor and she said it was a yeast infection and prescribed me diflucan. It felt okay a few days after but eventually went back to the way it was. I may be dehydrated from an antibiotic that was also prescribed to me, but my vagina is still in this miserable state, I don't know what to do, it's not normal and I'm very upset about it. :/ any advice is welcome