How to deal with concerned and curious well-wishers?

I'm new to Crohn's. Still in the process of being diagnosed. At this point I think I'm just waiting till we find a medication that works for the diagnosis to be official. Next week I start on azathioprine.
I work in a close-knit industry in my small community. As a result I have a pretty large number of acquaintances that are aware I have been pretty sick and been out of the office a large part of the past 4 months. I get questions all the time about how I'm doing, am I getting any better and have the doctors figured out what is wrong yet? I know everyone means the best and it is nice to know that people care, but on the other hand, I don't want to announce to the world what I'm going through! Is there a trick finding a balance of keeping some level of privacy, but not outcasting well-wishers?

If I want to be vague, I just tell them I'm dealing with autoimmune illness, attacking internal organs. People tend to understand that, as everyone knows someone who has some sort of autoimmune disorder.

And, if you take care to mention it's internal, that may help them to understand why they can't "see" your sickness.

Ivy.

I usually say what Ivy said I have an auto immune disease and leave at that. But that is with people i know will be all weird about if I actually tell them. But with others I have no shame, if they ask I tell. Others I just say I have Crohn's Disease and they don't ask anything about it so I just leave at that.

I'm pretty open with friends and people I'm closer to. For acquaintances and more distant colleagues really like Ivy's suggestion. I've heard so many times this summer "well, you look great!" due to the fact I'm down 30 lbs and have a nice tan because the most strenuous thing I can handle most the time is reading in the hammock in the sun! That should help people understand that things are going on internally without needing to give them the dirty details.
Thanks guys!