Why am I spotting blood out of my vagina when I go poop.?

So every time I go poop I spot blood I spot blood out of my vagina... and I am absolutely positive that it is coming out of my vagina... It is not alot just a very light pink but it is happening every time I poop. And it doesn't happen any other time... It hsd been going on for about two weeks now... Also I am on the depo shot snd not due to get my next shot for another month... and I am sexually active but even though I am still on the depo we still use a condom...