What Causes Pain In Abdomen Around The Navel?

I have had an ache or pain in my abdomen to the right of my belly button for a while it comes and goes!
My doctor sent me for an ultrasound and I did not hear any news from this (at least 6 months ago).
Right now while I am sitting here if I slouch it feels like there is something just under my rib cage like a knot or something (hard to explain exactly). Should I be concerned?