That sucks, man. Injuries are frustrating. I'm guessing that, after recovery, you are going to have to spend a lot of time warming up and stretching that muscle before doing anything.
I was actually doing more warmups then I ever had in my life already. Calf raises from a low heel point - hamstring stretches - couple more leg stretches too.. I "guess" the only other thing I could do differently is walk a few minutes too before jogging?
Pretty discouraging when considering the weiner pace I was jogging at anyway. Previously I had run 8+ mph on .5 to 1 mile runs on a treadmill as part of an HIIT thing I was doing - NEVER warmed up. Not sure but maybe the fact that I had not run on the road in 30 years got me.. WHo knows