What Can Be Reason For The Swelling In The Vagina When Pregnant?

hi i was just wondering if anybody could help?
i am 25 weeks pregnant with my second child, for a while now i have had swelling on both sides (outer, lower ) of my vagina, it is really painfull when walking and after sex especially sore, it feels as if something down there is going to burst.
i asked my mw to look, she did not examine it and just said that it is likely to be pressure from the baby, i dont think she understood just how much pain and discomfort this is causing me, any advice would be a huge help. naomi