My vagina is itching what could it be?

Could be Infection: The most common reason is vaginal yeast infection. Need to be checked also for other types of infections or causes. The antihistamine will help if the rash is due to allergy.

Yeast Infection?: The most common cause of vaginal itching is a yeast infection. You can try using a vaginal yeast medication for your symptoms. If this doesn't resolve the itching, you may need to see your Gyn for an exam because there are other causes such as skin conditions, other infections, even vaginal cancer. Best wishes!