when they were smaller i wouldnt even mention it as an illness...
i would say stuff like "mamas just mad about everything today. its not all your fault. just give me a little space today" or "i know i dont seem sick but i am very tired and dont feel well at all. i cant take you down to the park today but if you want to use the paints and make something at the dining room table that would be ok today. i know youd rather go out. sorry, maybe tomorrow but for sure on the weekend when daddys home ok?"

of course on days when we put on costuimes and face painted and had picnics under the dining room table or painted the bathroom walls with crazy designs they didnt seem to need any further explainations. hahaha!

it wasnt until they were older (mid teens) and i was having anual inpatient stays that we even gave it a name. it was just me always telling them what was going on instead of trying to cover it up or soldier on for their sake that made it understandable for them.