I feel like that too! I got a distinction in a module I took recently, and yesterday someone asked me some simple thing about it that I should have been able to reel off without effort. I drew a total blank, got it completely wrong, then spent the rest of the morning thinking about it and eventually scraped a general overview of it out of the depths of my memory. And it's something simple that I learned about -this year-.

I have no hope of rememebering anything from my previous degree, and I've forgotten so much of my professional training it's genuinely embarrassing. I used to enjoy teaching back when I was still learning myself, but now that I'm qualified it feels like everything's slipped back out of my head and I'm scared of being asked questions. I'm changing professions into something where lives aren't in my hands because I'm scared of my own inadequate brain.