While injuries are an obvious cause, sometimes that pain seems to come out of nowhere. When this happens, self-diagnosis is not a good idea but there are a few potential diagnoses that you may get at the doctor’s office. One of the most common causes is an issue with the rotator cuff tendon. This tendon can become inflamed during heavy repetitive workouts or due to long-term wear and tear. This condition is called rotator cuff tendinitis, and it’s one of the most common reasons why people come to our Singapore clinic. Long-term wear also affects your other body parts causing foot pains and lower back aches. Inside your joint, you have small sacs filled with fluid. They create a cushion between the soft tissue and the bone to reduce friction. When you overuse your shoulder, these sacs can become swollen and cause subacromial bursitis. In the case of acute injury, you can be dealing with the splitting and tearing of tendons. This is a common sudden injury or it might gradually come on as you get older. Similarly, instability can be the result of an injury or it may become an issue with increased wear and tear. If your pain has slowly worsened over the years, it could be caused by arthritis. Meanwhile, sudden intense pain could be the result of a fracture to your collarbone, an upper arm bone,  or a shoulder blade. You might be interested in these exercises to improve shoulder mobility and prevent muscle cramps.