my 10 month old cochin won't get up or eat

[Gennasgems]

I have /had 10 variety breeds that seemed to be thriving but my other cochin dropped dead a couple of weeks ago and now this one can't seem to stand. I've checked for egg bound or tenderness in any area but nothing. The rest of the flock is fine. I have searched 'symptoms' online and nothing seems to match. Help