My memory started declining while I was on Lithium. At first even though I always had an impeccable memory, I could find the humour when I tried, but it just steadily declined until it affected everything and drove me nuts, not to mention affected my self-esteem badly...

At one point I had to write down 3 items to purchase at a corner shop across the road, when I've never needed an entire shopping list when going to a mall before. I couldn't retain any information and it was really embarrassing. What killed it for me was that I forgot chunks of my extensive vocabulary and had to eventually relearn definitions and spellings, not only that, but I actually sustained some permanent gaps. In a nutshell, Lithium actually made me stupid at the end of the day. Apparantly I'm in the minority and meds don't usually stupify us. Either that or others don't admit it, are in denial, or are so affected that they don't even realize they've been dumbed down.
My point being... meds probably may not do to you what it did to me

But if you are sure there's a correlation with a med and your suddenly diminishing memory, well then I suggest a word with your pdoc to see if there is a better alternative than getting lost in your own car.

My memory started improving steadily after getting rid of the Lithium and besides the normal issues with racing thoughts and forgetting what I wanted to say or where I put something, I haven't had any "impacting my daily life" grade issue since.
My mega memory has officially been restored!

I'm really sorry you're experiencing this, I hope there's a workable solution for you.