What Causes Head Ache After A MRI Scan?

I have high blood pressure and recently i was admitted in hospital. the hospital did a ct scan and showed abnormality of white matter, followed by a lumber pucher which came out ok, the they did mri scan which had the same results to the ct scan. since then l have started having mild headache feeling weak and seeing shadows. am onamlodipine 10mg and bendroflumethiazide 2.5mg