What you seem to be describing are called "brain zaps" ... at least that's my general impression. Sometimes happens when going onto a drug, or as a withdrawal symptom. Not at all fun, and actually semi-serious as a side effect.

http://psychcentral.com/meds/tegretol.html
http://psychcentral.com/meds/effexor.html

If you're not having a good time with going off of the meds (did you do it cold turkey, or taper off?) ... I'd suggest talking to your prescribing doctor about this.