Hi & Welcome to HCM.
I have gone through the problems described in your query.
I am of the opinion that you have some sort of
fungal infection termed as
vaginal candidiasis (yeast infection).
This infection can be effectively treated by using anti fungal creams like
Clotrimazole or
Miconazole to be applied on the affected area for 2-3 days
Other effective treatment is single oral dose of antifungal drug
Fluconazole.
These medications are available over-the-counter.
The home remedy for such infection include:
A fresh garlic clove.
Take a clove of fresh garlic and peel off the natural white paper shell that covers it, leaving the clove intact.
At bedtime, put the clove into the vagina.
In the morning, remove the garlic clove and throw it in the toilet.
One night's treatment may be enough to kill the infection.
Continue one or two days until all itchiness is gone.
You can also eat yoghurt as this has proven to be effective in such cases.
Since your genital area is inflammed and painful, sitting in warm water (in a bathtub or sitz bath, not a hot tub) may help. Or instead, you may try putting a cool, damp cloth on the area.
Do not rub to try to relieve itching.
Use loose cotton cloth undergarments.
Hope the suggestions give could be useful in eradicating the infection.