What Causes Itching And Swelling In The Vagina?

Hi, I have a very bad itching and swolling on my vagina. I notice it started right after my last period was ended about a week ago. it just felt like sored at first but then started getting swollen in the inner labia. it really hurst for everything. it even hurts when I sit down. I am using vagisil but doesnt do anything. The iching and swollen still there. I dont know what to do