Vaginal itching is a very common problem. The fact that you have it despite allopathic medicines means that there is an underlying cause that needs to be looked at. (Like some mental stress/ some unexpressed emotion that you have).
Homeopathy acts on the person, not the disease, and that's why the right medicine can cure even "incurable" diseases.
Next Steps
Consult a homeopathic physician online through Practo. Tell them in detail about not your physical, but emotional problems. Don't worry, with the right medicine you'll feel better within days.