Hi...been Diagnosed With Severe Chronic Migraines.. Had Mri Etc.. Neurologist

Hi...been diagnosed with severe chronic migraines.. had mri etc.. Neurologist has given me nortriptyline ..started on 10 then gradually increased to 50mg...no change still have chronic migraines. I have been decreasing the tablets as due to change to topiramate .. experiencing dreadful side affects... head pressure is worse than ever...Is this due to dose decrease...also wlll the topiramate work better as I have been suffering for nearly 2 years...thank you