What Causes Growth Of Lump Inside The Vagina Along With Abdominal Cramps?

I am 25 years old and I have 3 kids. I realized that after my 3rd child I have a flesh wond on the inside of my vagina. It seems to be growing and it blocks the passage way in my vagina. When I have sex I get a lot of pains in my stomach. When I touch it no pains. Please help me understand.