My 2 month old baby still has black in her belly button. looks like dark skin instead of umbilical cord residue. is this common? when should it clear?

He'll Squeak By This: That's probably dead skin and it can take a fair while to slough off. Don't pull or pick at it. Just the usual bathing and time. At this point it shouldn't get infected or anything but if it does get red and inflamed or has discharge or bleeds, don't freak, just call your doctor. Also, if you squeeze your baby's belly and he squeaks via that area, then he'll be able to amuse himself real soon!

Not to worry: This will go away with time. It is not uncommon and with gentle cleaning using soap and water it should eventually wash away.