Are sharp pains in your vagina while pregnant a cause for concern?

[Brittanie Rivard]

I am 31 weeks pregnant and for about the past 5 days I have been having sharp, piercing pains in my vagina. When I stand is generally when I feel them and sometimes its so sharp that I get weak in my knees from the sudden pain. It literally feels like lightening bolts are striking me down there, as strange as that sounds. Any idea what this could be and is it normal?