Hi SoS,
I used to suffer with severe menstrual cramps for years,with vomiting & the whole works,it was so severe they removed my appendix at age 12,because they could not believe it was just cramps.Then it became obvious that I did not have monthly appendicitis with no appendix.
Anyway I can sympathise with your daughter & recommend the following things,
Magnesium taken before bed each night,B vitamin complex taken in the morning because can be energising,eating healthy foods that are rich in both calcium&magnesium like nuts,seeds,dark green leaefy vegetables.
Dairy produce is only rich in calcium but not magnesium,both are needed for the muscles during the shedding of the womb's lining.
Vitamin E can help reduce the cramps.
Essential polyunsaturated oils are likely to help if the pain is associated with a heavy blood loss with a tendency to clot.
Zinc might also help.A good multimineral &
vitamin every day &essential fats every day,maybe a pinch of the grey,mineral rich seasalt and 1 quater to a half teaspoon of blackstrap molasses on the days throughout menstruation,plenty fresh organic vegetables & animal protein if possible especially the week before menstruation.But not
too much red meat or dairy produce because these high-fat foods can interfere with prostaglandin balance,which controls blood thickness.

And to get through the cramps a hot water bottle ,maybe two,one on the front ,one at the lower back or wherever the pain, keep warm and
encourage her to breathe through her nose,
sipping camomile tea might help,that helped me greatly,
and trying to relax the body,tensing it or doubling over trying to fight it doubled the pain.

Sometimes the monthly cramps can be from oestrogen dominence,and lack of progesterone.
There are saliva tests for this.I wish I knew all this back then.
I was offered pain killers each month & on one occasion was given an emergency injection of morphine,my mam drove me home I was singing,telling her how much I loved her all the way home...