Anyone know what this is on my dog?

E.

I noticed this spot on my dogs belly near her vagina. It almost looks like a mole or birth mark, but I've never noticed it before. She has a vet appointment on Monday so I'm gonna ask then but I wanted to see if any of you ladies might know what it is. She just started going to a doggy daycare so I'm worried she might have picked something up there.

A better picture: