What Causes Stomach Pain, Back Pain And Nausea?

I have been going to a gastro. Dr for pain in right side in stomic and pain in back had a scan of gallbladder and was told it is not my gallbladder because I do not have gall stones. He then did a scope of my stomic That was also good . He then did a colonostpy that was also good. He also thought it might be a blockage of my artieries to my stomic also good.I have lost 21 pounds and get waves of nausea. I ate1/2 a meatball sandwich and thought I was going to die . All high foods bother me. I m eating Lipton noodle soup,jello,apple sauce,and bananas.My sister died 3 years ago from gallbladder cancer. He keeps saying I have IBS but my tests are good,and the medicine he gave me isn t working.It s been going on for about 1&1/2 months what can I do? He want s me to keep taking the meds for a month and then come see him again. I feel sick and don t know what to do. I can t send my results of my tests because I don t have a computer just an old iPad with only 3G.Can you help me?