Small arm pain can be caused by a variety of reasons, common excessive exercise, trauma, myofasciitis, cervical spondylosis. 1. Excessive exercise: excessive exercise of the upper limbs can cause lactic acid accumulation in the muscles of the small arms, physiological swelling and pain in the small arms, which can be relieved after resting. 2. Trauma: due to violent blows, strains, sprains, etc., can lead to local tissue bleeding, hematoma formation, small arm swelling and pain. 3. Myofasciitis: mostly seen in people who often work on the upper limbs, with corresponding chronic aseptic inflammation in the forearms and symptoms such as numbness, swelling and pain, weakness and so on. 4. Cervical spondylosis: when cervical disc herniation compresses the nerve root, small arm swelling and pain will also appear, and cervical spine X-ray examination, MRI and so on can make a clear diagnosis. There may be other causes of small arm pain, such as elbow tube syndrome, osteofascial compartment syndrome, etc. If the pain is not relieved after resting, it is recommended to go to the hospital in time, improve the examination to clarify the cause of the disease, and carry out targeted treatment under the guidance of the doctor, so as to avoid delaying the condition.