My bellybutton aches now and then - a dull pain - very uncomfortable and I can't wait for it to end. Any idea what causes this?

Hi There,

I am 31, female, in good health and not pregnant.  Every few months (and more recently of late), my belly button aches (internally - if that makes sense). It's a horrible and uncomfortable feeling which usually lasts about 15 minutes. Pressing it doesn't seem to help.

I would love to know what causes this and if you have any suggestions as to how I can avoid this in the future?

Thanks