Doing pelvic floor exercises causes pain in Si joint, I know muscle is attached to tail bone could the pulling of muscle cause Si joint dysfuncation?

SI Joint Disfunction. This is a common cause of low back pain. I treat several cases of it a day. Most of the time its from a strained ligament due to an accident or overuse injury. Different positions increase the pain. There are a lot of muscle attachments from the low back, hip and pelvis that can aggravate SI pain. Best results are achieved with a small injection of anesthetic and steroid into the ligaments.