What Causes Lump In The Abdomen With Severe Abdominal Pain And Diarrhea?

i have had horrible stomach pains for months and a huge lump right in the middle of my stomach. also more recently i have horrific lower back pain. earlier a terrible headache and pain in my left arm. the lump is scaring me and i had diarrhea for months, on and off. so bad i had to miss work. at times the pain made me wish i was dead.