Belly button pain

Has anyone has belly button pain postpartum ? I have had it on and off and usually it’s worse after doing ab exercises. It doesn’t hurt unless something rubs against it or for example if I’m leaning against a counter or I’m holding my son and he’s really pushing into my belly. It’s very sensitive and uncomfortable to touch. I was thinking it could be a small hernia, umbilical hernia maybe, but I don’t feel a bump or lump anywhere on my belly Has anyone ever experienced this and if so what doctor did you go to, general physical or OB? Thanks