I am experiencing vaginal itching and vaginal pain but! i heard of this pills metronidazole...so how many do i take and how long does it goes away?

MTZ won't help: Metronidazole is not likely to help these symptoms; don't take it. It sounds like you have either a severe yeast infection or maybe genital herpes. Don't screw around with this: see a doctor ASAP for accurate diagnosis and effective treatment. If it's herpes, treatment must be started right away in order to be effective. Good luck!