What Causes Big Brown Spots In Abdomen?

I have had a brown spot on my right abdomen for 8 months. it is about two inches by two inches. I now have another one in the middle of my abdomen below my navel. Areas are tender like bruises but dont reallh go away. Abdomen is a bit gender on the right side. Dont feel well after I eat and dont have much of an appetite but still remain over weight. Have had ultra sound done on liver, pancreas and gall bladder. Results negative. what should I do next?