I have a sharp pain in my belly button and it feels like something is pulling it from the inside. what is the cause of this pain?

Have an examination: Hard to tell without an examination. Is there a small bulge at the umbilicus? A small hernia is possible. See a doctor for an evaluation.

Umbilical hernia: Most likely cause of your symptoms is an umbilical hernia with fat caught in it. Do you notice a bulge in the umbilicus? A simple physical exam should determine if you have a hernia.