Thank you for choosing Doctorspring. I will be glad to help you.

I understand that you are concerned about the period like cramping pain that you experience for couple of hours after a long run.

You have provided me with good information about your problem , yet i may require you to answer a few of my queries about your condition so that I could help you out here.
1. Do you have any menstrual like bleeding that occurs after the cramping pain occurs?
2.Does the pain occur every time you run hard or does it occur only around the time of your period?
3.Do you normally have increased(out of proportion) bleeding and pain during your menstrual cycle?

If your answer to all my questions was a no, then in all probability you may not be experiencing a gynecological condition. You may then be experiencing lower abdominal cramps that may mimic a period like cramps that occurs usually due to wrong exercise practices.
The pain may occur due to dehydration after a long ,hard run or sometimes due to the pull of the tendons or ligaments during the running motion.Sometimes, this kind of pain can also occur due to an increased heart rate on exercise causing the blood flow to reduce in your lower abdomen causing pain.
I recommend that you follow the measures i have outlined below that may help your symptoms to improve.
1. Do not go for a run or exercise for at least 4 hours after a meal.
2. Drink adequate water with electrolytes( oral re-hydration solution or Gatorade) before, while and after running.
3.Warm up by some stretching exercises for at least 15 min before you start running.
4.Start off with a slow jog and gradually increase pace so that you give your heart enough time to acclimatize.

In case your answer to the above questions were a yes, I recommend you get back to us. You may then have to consult a gynecologist and have an ultrasound of your pelvis and abdomen done to detect any abnormality like endometriosis or a cyst.I would be glad to answer any more queries.

Hope this helps.