Tender belly button?

battybtags

I noticed today that the left side  of my belly button (inside-if I stick my finger inside and to the left) is sore and I sort of feel a little lump there.  Is this common after a vaginal birth? I dont remember having that with my c-section at all, but I was in so much pain after that anyways that I dont think I would have noticed. It just started today so I'm wondering if it had to do with my full exam (including internal) I had yesterday at the OB or if I did too much today. Anyone have this before?