Hi, Sunshine Superman!
I've heard that medications can stop working for some people after a while. My counselor actually mentioned this to me yesterday at our appointment...she told me not worry about it, however, because there were so many ones out there to try if the Zoloft's efficacy went out the door.
I'm glad you've got a good plan for tapering off the old/trying a new medication -- good luck! Let us know how things go :)
It would be great to feel fine again and get the cotton wool out of me brain and start thinking properly again! Even coffee or the daily can of my favourite Red Bull-type stimulant drink, Lipovitan, had started not to kickstart me into action anymore!