Weird numbness under my right rib

[JohnCU]

It happens when I sit down and am not sitting straight up, it's like something is pressing on something else and it's going numb. I can gradually feel it getting more and more numb. It usually goes away if I stand up or change positions...? It makes driving tough. I've googled and googled and can't come up with anything other than I'm 40~lbs over weight and it's pressing on something..