Belly button scab infection?

My 9 month old baby's belly button is black and i read in other online groups that mothers just put baby oil in the belly button and used a q-tip to gently rub away. I tried it. It worked. It was coming away. But then.. the black bit moved to the side and i saw some white.. I freaked out and stopped. Baby is fine he didn't make a sound. He had an umbilical hernia which went away when he was 3 months old. So i know his belly button healed. Right? It didn't open up again? Is it infected? No redness or swelling and no smell.

No mom shaming!