If meditation brings a headache, you should not meditate. It is a mistake to think that meditation is indispensable to the Sadhana. There are so many who do not do it, but they are near to the Mother and progress as well as those who have long meditations.
The one thing necessary is to be turned to the Mother and that is all that is needed. Do not fear or be sad, but let the Mother do quietly her work in you and through you and all will be well.
Ref : The Mother with Letters on The Mother