Slight pain -comes and goes right upper side of abdomenp-more on the back.?

Kidney maybe. Pain in that area could be a kidney stone or could be gallbladder, especially if associated with fatty foods and accompanied by nausea and vomiting. If kidney stone the pain may get much worse and there may be blood in urine. Gallbladder may eventually cause right sided chest and arm pain. A good history, physical and some diagnostic testing can usually determine the cause fairly easily.