Buttock pain is normal during the third trimester of pregnancy due to pregnancy hormones that loosen joints in the pelvis and the additional weight, according to Healthline. The uterus grows larger, presses on the sciatic nerve, and causes buttock and hip pain. Patients ease the pain by applying heat.
Even though a variety of tests such as X-rays, MRIs and nerve studies produce normal results, runners may experience buttock pain resulting from an inflamed piriformis muscle, according to Runner's World. The muscle is attached to the greater trochanter, which is a protrusion of bone on the side of the thigh. When a runner forcibly rotates the hip while running on uneven terrain, falls on the buttocks, or overuses the muscles, the piriformis can become inflamed, which leads to pain in the central buttock.