Hamstring Strain

About 5 weeks ago, I strained my hamstring running intervals on the track. This was the first hamstring injury for me. I did the RICE regimen and took 2 weeks off from running. I also did stretching and strengthening. I started back at that point 2 weeks after the injury and slowly built up to a 5 mile run last week when WHAM, the same strain.

Now, I believe this is a mild strain as I could walk without any ache or pain the next day.

So now I am back to two weeks of Round II of RICE and no running with stretching and strengthening.

Should I wait longer before I try again? What have other folks done to get over this injury?

Thanks!