with all the talk about stretching out of the way, you really should strengthen the hamstrings and glutes. gradual, long-term strengthening of the muscle will also make the connective tissue more resilient. For pulling hamstrings while running, that could be due to weakness in hammies and/or glutes, or glute inactivity leading to over recruitment of the hammies. We all do squats or some variation; deadlifts and hip raises are also a must to maintain balance across the hip.

Personally, I've had the best luck with ibuprofen for halting inflammatory processes. I've iced, gotten little results, and took one large dose (1000 mg) and was noticeably better the next day. It's worked on a few sprains, and most recently a lumbar strain. Think I'll do a century tomorrow, in fact.