C.G.
If you have never had a yeast infection before you should call your doctor or midwife so they can diagnose it- it could be something else. Just using vagisil cream would likely not be that effective as the yeast would most likely be internal to the vagina and you would need one of the yeast infection treatment packs. It is possible to have ueast only on the vulva but unlikely.
Bacterial vaginosis is another problem that women get that is not sexually transmitte. Like yeast it is an overgrowth of normal vaginal inhabitants. Antibiotics are used to treat BV. Vaginitis is an irritation of the vagina- if you have recently changed soaps, douched, changed laundry detergent, or anything else that would be in contact with that area of your body they could be causing your itching. Douches are very irritating to the vagina and soap is a very common culprit in vagina irritation.