Hi, thanks for writing to HCM. Based on your description of findings, most possibly you might have developed a Hematoma (blood clot) at the site of injury that is presenting as a large bump. Generally, these hematoma s will resolve spontaneously within 2-3 weeks without any complications. But they is every likely possibility that they become infected, especially in Diabetic patients and may pose problems. An xray of the sacrum will show the presence/absence of any bony injury. The general treatment guidelines for your condition are as follows - * Take over-the-counter pain relievers, such as acetaminophen (Tylenol), ibuprofen (Advil) * Apply heat or ice to the affected area * Use a doughnut-shaped pillow/cushion beneath, while in sitting position * Lean forward while sitting down * Sit completely upright with proper posture — keeping your back firmly against the chair, knees level with your hips, feet flat on the floor Hope this information is helpful. Good day