Fils,
First, welcome to the forum! Tho I am terribly sorry for what brings you here!!
Something indeed sounds 'amis'....aka NOT RIGHT!
Seems complete RUBBISH for her Dr to want to take out the system this soon! Seems pre-mature to say the very least, especially since the unit was working fine at first!!
There could be a number of factors......scar tissue forming, migration, or just a bit of simple adjusting to her program settings.....lowering the amplitude....

Does she notice these 'shocks' when she moves her head a certain way?
Or while she is in a certain position?

This Dr needs to be accountable for his work!! And (unless infection or something drastic as such) there is NO way he should be suggesting to take the unit OUT!!

I 'second' Mark's suggestion and get a second opinion asap.....
For the meantime, maybe just have your mom turn the unit clear down or even 'off' it need be........

Please keep us posted!
Caring
Rae