What could cause right shoulder pain/injury?

Variable: The pain could be things as simple as a contusion, tendonitis internal derangements, and fractures. You need a thorough exam, history and possible xrays or MRI scans obviously , the results of the above will help determine the best treatment.

Many causes : There are many causes of shoulder pain, some coming from the shoulder and others referred to the shoulder. If you have a more specific question...