Brain Zap/Shivers?

I'm a 40 yr old female with daily occurances of what feel like a zapping in my head. This has been going on for over a year now.  I've found some info regarding "Brain Shivers" which seem to describe what I'm feeling during the episodes.  I am not on any anti-depressant medication, nor have I been in the past.  Current meds are Klor-Con 10 for low potassium and Hydrochlorothiazide for bp that was high in the past, but has been normal/low over last several months.  

My question is if there are any other known causes for the 'brain shivers/zaps'?  I experienced my worst one yet last night...very frightening.  Most of what I've read indicate that the "brain shivers/zaps" are usually related to withdrawl (withdrawal) from certain meds.  

I understand that Hydrochlorothiazide can cause dizziness, but these episodes are much more than dizziness.  It's like someone is shocking me.  Lasts about 15 seconds and then it's gone.  Last nights zap was much more intense than ever and I was still feeling the after effects for a couple of hours (tremors in hands, slight headache).

Thanks in advance for any help you can provide.  My fear is that these episodes are clearly getting worse and I don't want it to happen while I'm driving.

[jojo5397]

Hi my name is Joanna and I just found out the episodes I have  are brain shivers they
come on real fast. I told the docters what it is and they never heard it. I did my search
and I think it is from my med's.I am afraid to drive with it. Do you know if it is safe to drive?My brain shivers are getting worst I have them almost every day. I just want to close my eyes and not get up. I do not get them when I sleep only if I turn my head.