You definitely should see a doctor about a rotator cuff injury/tear, especially if you had immediate weakness in your arm after an injury. The sooner you seek care, the better. We can help you here at Specialty Medical Center! It's important to see a doctor or specialist right away because if a rotator cuff injury isn't treated soon, it can lead to permanent loss of motion or weakness and might even lead to the progressive degeneration of the shoulder joint. Also, if you try to keep your shoulder immobilized for too long, it can cause frozen shoulders. With proper, professional treatment, though, such issues can be avoided and your injury can heal effectively. Typically, it will take a number of weeks or months to heal, but it will almost certainly heal.