Sudden shoulder pain may be related to the following causes: 1. There may be frozen shoulder. This condition is often caused by previous shoulder trauma, cold or strain, which may lead to aseptic inflammation around the shoulder joint. 2. When rheumatism, rheumatoid arthritis, or gouty arthritis strikes, it may involve the shoulder joint and cause sudden pain in the shoulder joint. For example, during an attack of gouty arthritis, there may be significant redness, swelling, and heat in the shoulder joint. 3. It may be caused by peripheral neuropathy. For this part, it is most commonly caused by neurogenic cervical spondylosis. During the onset of cervical spondylosis, if the nerve roots of the cervical spine are stimulated by compression, it is possible that radioactive pain will be produced in the shoulder or other parts of the upper limbs, and it will come on suddenly.