I'm 62 Years Old. I'm Over Weight. My Stomach Is

I'm 62 years old. I'm over weight. My stomach is aching. I haven't eaten a full meal since Easter. The only thing that sounds good is cold water. My stools are very dark. I just feel like curling up in a ball and lying down. Anything I eat just causes pain in my gut. I tried Nexium. Seemed to help for a bit. Not anymore.