Rotator cuff injuries cause pain in your shoulder and upper arm. The pain may be most noticeable when you reach up or out. When you turn your arm as you lift it, the tendons are more likely to rub against surrounding structures.
The essential difference between the original series of AF Nikkor lenses and all AF lens types introduced subsequently, from the AF-D versions onwards (see below), concerns the compatibility of a particular lens with Nikon's enhanced Matrix metering system known as 3D Matrix metering that was introduced during 1996.
Few of the D lenses range also have AF-S. These lenses will be able to auto-focus on the entry level Nikon cameras including the D5100. The 300mm f/4D AF-S is an example of this which is currently available. The D lenses are also somewhat cheaper compared to the G lenses.