Bad itching inside vagina. How is it possible to itch that far inside one's body?

Vaginal Itch. Most of these are from candida, a fungus or yeast. It can go way up the vaginal canal. Typical symptoms are itch and whitish discharge, sometimes looking like cottage cheese. Typically does not have an odor. Over the counter treatments include monistat, vagistat (tioconazole). Prescriptions include terazol, diflucan. Some use boric acid and gentian purple.
Yeast infection. You likely have a yeast infection. It commonly causes itching. You have nerve fibers throughout your body including the vagina. The inflammation from the infection causes the itching sensation.