There's a lot of crap written about period pain treatment, (because there is probably a lot of money involved in its treatment.)
Basically, the evidence suggests;
1st line : Paracetamol - very effective and safe drug in its correct dosage. (Remember to take 4gms a day, once you wait for the pain, it will be harder to treat.)
2nd Line : Ibuprofen (Remember this can be taken with paracetamol)
3rd Line : Mefanamic acid (Available in UK only on prescription)
I'm not sure how these drugs fit in with the regulatory frameworks for aviation.
Beware the snake oil salesmen ! Good luck.