Google, issues with your lady parts probably tops your list of whys. Still, we know you might still be tempted to do a little digging while you wait for your appointment to arrive, of course , so here are some common reasons you may have a lump or bump on your vagina. This is one of the most common causes for bumps on the genital region. When a pubic hair grows back into the skin instead of popping up out of the surface, it can form a small bump that may look red, says Dr. Though innocent enough, hair bumps can be itchy, tender when swollen, and even filled with pus.