Hi my 15 year old daughter has been having her periods for the last year and they are pretty regular, for the last 3 months she has experienced very sudden onset of partually blurred vision in her left eye followed within 15-30 minutes of a headache and nausea this can also include vomitting, she goes pale but has normally gone to sleep then felt better after waking, these have happened within a week of her period. She is normally fit, well and very active, she is 6ft tall and weighs just under 10 stone. Are these episodes simply related to hormonal changes prior to her periods?