See if this stretch helps: www.youtube.com/watch?v=2qZ517Rw7ME
Do it for 30 seconds hourly.
Also go over it with a foam roller or tennis ball, medicine ball, etc., like this: www.youtube.com/watch?v=HWfnAUsYUTI
If that doesn't help, see a doctor or physical therapist.
Since you're 50% over your ideal weight, running creates a lot more stress on the body than if you were lighter, increasing the chance of injuries. Personally i wouldn't run long distances until you're within 20% of your ideal weight. There are lots of other ways to exercise.