Pain on the right side flank in my back have been seen three times and they can't figure it out any ideas?

Right flank pain: Not enough information to really give a good idea w/o re-inventing wheel. Simple common things include kidney infection/stone, gall bladder & liver problems, ulcer, lower lobe pneumonia, muscle strain, shingles, peptic ulcer, irritable bowel, inflammatory bowel, gluten sensitivity, fitz-hugh-curtis syndrome, appendicitis, ovarian cysts (last two are more likely lower quadrant than flank), etc.