Migraine, please help

Hi,

My mum has been suffering from severe migraines for as long as I can remember, they are so bad that every time she has one the doctor has to be called so he can give her injections to stop the vomiting and also give her a pain relieving one. She is a tiny woman both in weight and height and these migraines are really taking their toll on her. She has had every test possible and watched for triggers etc but nothing has been found. The migraines can just attack at any given time. She knows they are about to start as she starts to go 'blind' and then she has to take her strong medicine which she pumps up her nose, however these have began to be less effective as she is using them more frequently. Headaches are there all the time but the severe ones are happening about one a month. I would love to find her something that she could take everyday that would keep the headaches away or at least tame them down a bit. If you need any more info please just ask, we are desparate for some help. Thank you so much.