A 37-year-old patient complains of general weakness, spastic pain in the lower segments of the abdomen, mainly in the left iliac region, and loose stools with mucus and blood up to 18 times a day. The disease onset was acute and occurred three days ago with chills, feeling hot, and a headache. The patient's general condition is moderately severe, body temperature - 37.8°C, Palpation detects spastic and painful sigmoid colon. What is the most likely diagnosis in this case?