Chaos, sorry about your biggie...stuff like that sucks. It's a fine line to walk - I agree with Renee abut explaining to your boss about how the CRPS can affect your memory....but I wouldn't make it sound too serious in case he then thinks he cant trust you with anything

Work stuff is a nightmare in that regard, and you do have to be careful. Of course your boss should accept any limitations from your medical condition and not penalise you for them, but we know that in practice that can mean many things. It all depends what sort of guy/gal they are, and whether they will let you continue the same work...
Sorry. I'm not saying you have to lie, or that because you made this mistake you have to go and count beans in a corner or something...just that you need to be careful with how you explain this.
For work stuff, I write everything I need to do down in a little diary that I carry everywhere to remind me. Otherwise I forget all sorts - it's saved my bacon many times. I'm lucky it's just me now though, and I don't have a boss - although it can still cost me a lot in money and reputation if I mess up.
Good luck and keep smiling. I still think you are doing great to be working at all considering what you are dealing with. Be proud of that.
Bram.