Evaluate your pain level. On a typical medical pain scale the 0-3 range covers "no pain" to pain that you only notice if you think about it. 4-6 is noticable even if you're not paying attention to your body, and will have moderate effects on your mood. 7 and up is very serious, and can leave you moaning, crying or suicidal. Pain higher than 7 may cause vomiting or other serious physical effects. 10 is the worst pain you've ever felt.

If your cramps are in the 0-3 range, you can probably get away with no medication.

If your pain is in the 4-6 range, I would recommend medication. For most women, excercise will not be sufficient by itself to alleviate that degree of menstrual pain. The pain medication will help your mood, and make it easier to excercise. The combo of excercise and pain medication will mean you need less medication and will have much less severe mood effects.

If your pain is in the 7 and up range, see a doctor. Pain at that level is dangerous, and cramp pain can continue for 4-5 days. If I try to go without medication, my pain level would hit a 9 and stay there for at least 4-5 days, complete with vomiting, moaning, and a strong dose of suicidal thoughts. I've hit a 10 on broken bones, but the pain of a broken bone doesn't stay at 10 for anywhere near as long as cramps stay at 9. Ordinarily pain in the 7 and up range is grounds for immediate hospitalization.

Don't screw around with your pain. It's real. You deserve a body that doesn't hurt. It's okay to say "I need to medicate". Sometimes medication is the only way to get functional enough that excercise and stretches can help.