Rotator Cuff Exercises http://rotatorcuffexcercises101.blogspot.com/20... Have you ever experienced a dull ache or sharp pain in your shoulder or upper arm? Maybe you are unable to sleep on one side because your shoulder wakes you up at night. Perhaps, you have discomfort reaching behind your back to tuck in your shirt or grab your wallet. If so, you may be suffering from a rotator cuff injury.