Welcome to HCM.
Normal range of menstrual cycle ranges from 21 days to 35 days and differs in different women. There are medications which can be taken to post pone periods but they are not without side effects. I would suggest not to worry much if the periods are regular with normal bleeding pattern. Tab Meftal spas
can be taken to deal with the spasmodic pain occurring during periods. There are few stretching exercises to reduce pain which can help to some extent. Tell her to lie down on the stomach and lift both arms and legs in air to get maximum stretch in the abdominal areas. This position can be maintained from 10-15 seconds. Another version is lifting opposite arm and leg while lying down on the stomach which will reduce the pain. I hope I have answered your query satisfactorily. Thanks.