Stomache Pains

I have had extreme pains in my stomache since I was 16. I'm 22 now and they seem to get worse. I really notice the "attacks" after I have consumed alcohol or ate something my stomache disagreed with. The pains seem to peak after a while and then go away after 20- 45 minutes. The pains make my whole back uncomfortable and sore. I can barely make it through some of the"attacks" and I have had many tests done. The only thing that has been detected is that I have an enlarged spleen. Sometimes I throw up straight bial. All my test keep coming back normal and the doctor bills keep getting more expensive. Any suggestions?