I think a serotonin med (like an SSRI) will get rid of the brain zaps. I take Cymbalta (similar) and have read a lot about tapering. Lots of the taper info. says to taper by 10% each time you cut the dose, so that would make you go from 37.5 mg to about 33-34 mg. Some people have to go that slowly to make their withdrawal symptoms manageable.

There are some sites online about nutritional supplements to help with the withdrawal symptoms, too, but I have not tried them. 5-HTP might help.

I hope you get rid of the symptoms. I tapered from 120 mg/day Cymbalta to 60 mg/day last year and it took me 5 months. Those SNRIs are tough meds to get off of and Effexor is the worst.