Why is this? I've read it can be hemroids or cancer. The other night ago I took some vicodin with some rum, would that have anything to do with it? About the sharp pain in my arms, I will have sharp pain shoot up and down my right arm, then a little later on, my left arm will do the same thing. Never both arms at same time. The bloody stool thing started just tonight. The sharp pain in my arms has been going on for about 2 months now.