I surfer from severe headaches on a monthly pattern?

Hi im posting this on behalf of my wife. she suffers from severe headaches every month like in a pattern they get so sever she just has to go to bed and lie there for 2 days which is more or less how long it lasts the headaches last for 3 or 4 days then they go away till t happens again in 3 or 4 weeks...she has had a brian scan and its all clear..shes 52 so don't know if it could be related to the menopause or even her eyesight cause she sometimes looks as she is forcing her eyesight... plz no guessing replays i need formal replys thanks