I have this pain in my right upper abdomen that is only present when I sit upright at the computer for extended periods.I first noticed it about three weeks ago. If I lean back it alleviates the pain. The approx. location is three inches below my breast bone and two inches to the right. It is best described as a muscle ache similar to doing to many sit-ups. Any suggestions? Should I be concerned?

Go to the doctor... I had similar pains when I had gallstones... which led to my gall bladder being removed. It could just be a muscle strain... but I'd go to make sure.