Some combination of these worked very well for my cramps to ease over the past couple years:

• avoiding pads and tampons - I use a cup
• walking barefoot to ground and offering my blood to the earth when possible, overall reframing my relationship with my cycle
• gentle yoga especially malasana and related movements (crow walking, abdominal stretch pose), pawanmuktasana, happy baby, cat/cow, practicing deep breathing and bandhas regularly