I went to see a physical therapist yesterday. He got me on the massage table and did myofascial release therapy. Ischial Tuberosity is the bony part of the bottom of your ass that you sit on (one for each cheek). The hamstring originates there, so he really nailed the muscle for an hour and I was screaming, then he prescribed some hamstring and butt stretches. Will be back to see him again in a week. He said if I had continued sprinting, the hamstring would likely tear at that butt bone. The massage really relieved a lot of the pain and tension.