It's always a tough call: do you tell your boss when you're flaring? There's no one right answer. It depends on your profession, your job, and (perhaps most importantly of all) your boss. I've been super-lucky to have fantastic bosses, so I've not had too much trouble with this question, but recently it came up again.
On the one hand, I want to be the professional, independent woman who doesn't let personal problems impact my work. On the other hand, that's total bull**** in real life. Finally the choice was made for me: someone else asked how I was doing, because I looked really "tired" (aka "like death partially warmed over"). In my mind, if a coworker notices I look sick, then my boss surely has too. So, it becomes a different choice: do I risk letting my boss think I'm a drug addict, or do I 'fess up to having central nervous system problems? I chose to 'fess up.
Have I mentioned I have had (and currently have) great bosses? My current boss was totally understanding, and even suggested using her pilates mat as a mattress to keep under my desk. I'm going to go with my backpacking air mattress, but it was a nice thought. I do realize that I am extraordinarily lucky to have a nice boss and be in a profession wherein no physical labor is required. But it's still hard to break down that cool, independent professional image enough to say, "You know what? I'm really freakin' sick." I can only imagine how much harder it is for people who risk losing their jobs over their illness. That risk is fairly minimal for me; it wouldn't look good in court for the group in charge of Chronic Illness Prevention and Control to fire someone for having a Chronic Illness.
I know many of you have had this do I/don't I tell my boss dilemma. What did you decide, and what was the outcome?