low csf pressure migraines and Cadesartan... how effective is this meds for this type of migraine

I had a Thunderclap headache a year ago.. MRI/A & battery of tests conclude no reason for Thunderclap, ruled out stroke, buldging brain vessels. Had residual daily headpain 4/5 on pain scale. Put on Topomax for 9 months, titrated to max dose of 100 mg per day for 90 days. Made things worse--really, really bad!! Weaned off. Now neurologist believes that I have chronic low csf pressure migraines. It took 85 minutes to get spinal fluid during Thunderclap episode.  Put on Candesartan today, titrating up to 16mg/day by neurologist who specializes in Head pain treatment.. I am at the end of my rope and currently off work on sick leave.. How can I increase my csf???   How effective is this meds in treating low pressure CSF migraines and is there anything else I can do?? thanks