upper abdominal pain

I've been suffering from this for almost a year now.  I was at work one day and all of a sudden I got what felt like a "side ache" in my upper right abdomen.  It lasted about 20 minutes but went away once I sat down and relaxed.  That happened a couple more times.  Some weeks later I was sitting down, bent over putting on my shoes when all of a sudden I experienced what felt like a cramp/charley horse in the same area.  It hurt!  It didn't last long but I had a few more off and on as time went on.  I have been suffering from heartburn for years.  Within the last ten years or so I've gradually went from 185 lbs. to 260 lbs.!  I finally went to my doctor last week for an exam.  I had a pap test, mammography, blood work, chest x-ray and they did a sonogram on my abdomen to check for gallstones.  Everything came back normal.  They said my gallbladder looked fine.  The pain I'm having is a dull pain that goes into my back on the right side.  I always know it's there.  The pain does get worse at times.  It seems to get worse when I sit at my computer on a straight-back chair.  My doctor referred me to a general surgeon who I see tomorrow.  Do you have any idea what could be wrong with me?  I'm so tired of hurting.  By the way I'n 53 and I smoke.  Could I have torn muscles or cartilage?

[crambone]

i get same basic thing except mine is more center,and goes through to my back,,,i too have put on some weight over the years and i too think its worse when sitting down!,,,i have had thousands of dollars worth of tests,so if you ever figure out thats wrong with you,please let m know,maby we are one in the same?
mine comes and goes,and usualy only lasts a few minutes also.
one part of me thinks its gastro,,like gerd/gasteritis,,and another thinks its muscular/skeletal.
but its not my heart,gullbladder (gallbladder),pancreas exct,so what the heck is it?
i have had ct scans barrium swallow,all the blood work you could imagine,,,nothing shows up,,i guess thats a good thing,but i still get it,,also no ulcers or diabetes.