Feeling sore and swollen in the buttocks is usually caused by the following reasons: firstly, it may be caused by chronic strain or chronic aseptic inflammation of the buttocks muscles, which is common among people who have been doing lower limb sports for a long time, or people who have been doing squatting for a long time, because the muscles of the buttocks often have to exert themselves, thus causing strain. Secondly, it may be more common in people who often sit to work and live, because often sitting to work and live, the muscles or soft tissues of the buttocks are often compressed, which leads to some local sterile inflammation, and also the feeling of soreness and swelling. Thirdly, it may be caused by a herniated lumbar disc. If a herniated lumbar disc compresses the nerve root on one side, abnormal nerve sensation in the buttocks and lower limbs may occur, and a feeling of soreness and swelling in the buttock muscles may also occur.