As you still have a severe injury, proceed with caution. Actually this is a good time to figure out the problem. When you hit the right spot you will get more pain or some relief. I am not allowed to post direct link.
Your hip flexor is tight. This will compress your lower back as well as give you hip issues. Even healthy people need to do this once a week for ONE HALF HOUR per LEG! Could be also one side is tighter than the other so check for that.
1) "Progressive groin stretch" (Do a Google search)
Your piriformis muscle is tight:
2) "[PDF] Seated Hip Stretch" (Do a Google search for the one by "motionwise"
Also check on your own to see if one leg turns OUTWARDS easier than the other. If so, you will find the other leg does not turn INWARDS as well as the other.
Your hamstring is tight. Again, check to see if one leg is tighter than the other.
3) "lie on back hamstring stretch with strap" (Do a Google search)
Depending on how these work, if you are motivated, I can give you 3 more. There IS some trial and error. Also what works today may not work tomorrow and you will need / respond to another exercise.