Ah yes... every family has them... I get that all the time - I look fine, normal, great, etc. so why can't I work etc.
When I got terminated from work for being out exceeding the limit, my FIL asked why not go back?
http://www.invisibledisabilities.org/booklet.htm has a pretty good booklet just to hand out to those who give you those silly statements - but in truth, until there is a magic wand of "in my shoes" no one will understand.

I would love to use the wand on a few docs.