Not a doctor but your symptoms don't really sound like a stress fracture to me. (I'm not sure if your Post Stress Fracture ? title implies that you are recovering from a stress fracture and have new symptoms or is asking whether your current symptoms might be a stress fracture. But anyways)
I've had two femoral stress fractures eventually diagnosed by x-ray and bone scan after significant and longstanding pain. Stress fracture pain generally takes a minute or two to start and then does not go away. You can mentally adjust to deal with the pain (for a while) but it definitely doesn't disappear.
Can you run fast without pain once you are warmed up? If you can, it is almost certainly not a stress fracture as the main symptom I remember (other than the pain itself) was the inability to switch gears and run at a sprint or race pace.
It may be as simple as bursitis (inflammation at your hip joint) or IT band syndrome. Running exclusively on dirt and grass could contribute to some hip instability.
Try these simple stretches if you don't already. Lay on your side one leg on top of the other and raise your top leg straight up to a 45 degree angle and hold for 5 seconds. Do 2 sets of ten both sides once in AM and once before PM workout. Add a crossed leg standing toe touch stretch for 30 seconds each side at a light stretch. Both of these exercises are simple and won't hurt anything even if the pain is something more serious. You can google IT band exercises for all sorts of stuff but I think starting simple is the best approach.
These exercises have helped me with some general hip stiffness/ pain in the past. If the pain starts to persist/increase during run or makes you limp see a trainer or doctor. Good luck-