Soreness in the upper part of the tailbone is considered to be muscle strain, periostitis, soft tissue infection, ankylosing spondylitis, lumbar disc herniation and so on. 1. Muscle strain: prolonged bending will cause muscle and ligament strain in the sacrococcygeal area, which will be aggravated after exertion and alleviated after rest, and the symptoms can be improved by hot compresses and massage. 2. Osteochondritis dissecans: because of long time sitting, localized pressure periosteum occurs aseptic inflammation will appear sore, especially the body type is thin people, long time to sit on the hard seat. 3. Soft tissue infection: for example, the hidden hair sinus infection, localized pus can also appear local soreness, accompanied by skin redness, fever. 4. Ankylosing spondylitis: mainly involving the sacroiliac joints, mainly for the pain when sleeping at night, the spine and the upper part of the tailbone pain. 5. Lumbar disc herniation: If the lumbar disc herniation presses on the nerves, it can cause lumbosacral and caudal vertebrae pain, and can radiate pain and numbness to the legs. There are other causes of pain in the upper tailbone, such as trauma, etc., if rest does not relieve, it is recommended to go to the hospital in a timely manner, improve the relevant examinations, a clear diagnosis, and then follow the doctor’s instructions for targeted treatment, so as not to delay the condition.