My navel is hurting for the first time while my period is on - can you tell me why?

No... it could be totally unrelated. If related, it could be many things, but it's common when swollen to have various nerve pain just about anywhere. For it to be something rare and serious you would have to have tests and examination. A doctor might tell you to wait until your period is over and to take tylenol meanwhile. If you have a fever or inflammation, then be seen sooner.
Could you be pregnant?