I got the depo shot almost 2 months ago and sex just started to hurt really bad..?

Ok so almost every time we have sex now, i get so sore :( especially when he is first going in. About a week ago, we used vaseline and it worked amazingly. Since then, we've been using it to lubricate but sex hurts really bad now. Could it be the shot? I know some people say the shot makes sex painful, but how come it wasn't this bad before? Please help. :(