"Shoulder sprain", Per MM on post game show. Nothing further on the severity.
From the web: Grade I shoulder sprain, your discomfort should ease within one to two weeks, and you will be able to resume normal activities as soon as you can move your shoulder through its normal range of motion without pain. If you have a Grade II sprain, your discomfort should lessen within two weeks, but it may take as long as six to eight weeks before you can return to your usual athletic activities. People with Grade III shoulder sprains often return to work within four weeks. Athletes who participate in contact sports, however, have a high risk of injuring the area again, so they often need three to five months of rehabilitation before returning to their sport."