A 19-year-old male presents to the clinic with complaints of low back pain ongoing for 2 weeks. He recently had a skateboarding accident where he fractured his right radius. He states that he has run out of the opioid pain medication given to him by the Emergency Department and that he had not noticed the back pain until now. While the patient is seated, the posterior superior iliac spines are palpated bilaterally. The patient is asked to bend forward as if to touch his toes. The right and left posterior superior iliac spines move at the same time and to the same distance. A lumbosacral spring test is found to be positive. Given the exam findings, which of the following is the most likely diagnosis of the patient’s sacral somatic dysfunction?