I have no Alzheimer's but I must forget that I keep forgetting

I think I have memory loss. Or selective amnesia. Or Dory syndrome. Ok, so I coined the last one (actually I didn't, it's not even original. Who cares? What is?) I'm sure I'm not old enough or sick enough to have Alzheimer's. Or am I? Anyway... I have a knack for forgetting things, except those things I WANT to forget. It's like when your computer crashes, and the things you LEAST want to be corrupted are, guess what? corrupted. Completely bad-sectorised. Computrash. Or whatever you want to call it. Why? I used to have a splendid memory. Almost photographic. Heck, I remember remembering that I could remember the picture that I drew when I was 5 (or 6, my memory fails me) and Mom dismissed with a pleasant "Oh that's nice". It was a (badly-drawn) picture of a wizard complete with stereotyped cone shaped hat holding a stereotyped staff with a stereotyped orb held in a stereotyped dragon's claw BUT I WAS FIVE WASN'T I?!!?! (or 6.) And it was shooting this stereotyped (straight) beam of light out of it into something that looked like a cross between a dragon, a snake and a (badly-drawn) dog. And get this; it was SHADED. Y'know, shadows and all, in, er, shadowy places. I thought (then) it was rather imaginative of me. After all I'd drawn it from (you guessed it) memory. (Remember Dungeons and Dragons? The cartoon? With the wimpy sorcerer and his green hat? Wait... he didn't have a staff... or a beard... er...) You're waiting for a point to this story aren't you? There isn't one. So go back to work. Or try drawing something from memory before you forget about it. Like me. Or better yet, forget about it. Really.