Epsom Salt has warnings on it usually not to use if you have abdominal pain or kidney ailments. Try fasting and enemas.
I've had the same kind of pain, same spot in the lower right actually, right where the appendix is. Horrible shooting, cramping pain with some nausea. It usually was bad for 15 minutes then got better, maybe came back later. I've had it a few times in the last year, but not since changing my diet drastically and paying attention to my bowels. If you have a constant tenderness that doesn't go away then go to a hospital or at least a doctor.