Many different types of injury can occur while someone is running. Although a certain amount of stiffness plus sore and tightened muscles is normal when training, it shouldn’t last for days and days on end.
As in the case of any kind of sports injury, correct diagnosis is fundamental to successful recovery. Check whether the problem is caused by inappropriate or poor quality running shoes - a very common issue specially here in NYC, poor or bad nutrition or insufficient preparation. Also keep in your mind that even when your injury has healed, it will take time and patience to get back to your normal.
Hamstring tendonitis is a common problem for every runner. One solution that's recommended by professionals is doing hamstring curls, an exercise which allows you to isolate the injured muscles selectively. However, for this you will need access to a hamstring curl machine (available at Club Fitness NY) and care is needed to avoid knee damage while performing the exercise. If in doubt, reduce the weights and focus on the motion.
Acupuncture is known to reduce pain by stimulating blood flow to muscles and connective tissue as well as activating the body’s natural pain killers. This results in increased energy, better sleep and a healthier appetite, all of which makes you a better runner.
Pilates exercises are good for long-term strengthening and core muscle development right down to your joints and extremities. Imbalanced back muscles are often a cause of injury while training. Pilates exercises can re-balance those muscles by stretching and strengthening the spine and joints.
Finally, listen to what your body is trying to say to you. If you have some discomfort back off for a while. When recovering from an injury be cautious and focus on a slow increase in mileage and intensity of your run.