9 week old guinea lethargic and not walking - Assist please

[GuineaNana]

This morning one of my 9 week old guineas (of a flock of 10) would not get up and I was able to catch and hold him easily (they don't usually like to be touched). I don't feel anything lumps in the crop and visual inspection of the legs doesn't reveal anything, but he won't (can't) get up and walk around. What are the next steps? Thank you!

 

[Eggcessive]

I have no knowledge of guinea fowl, but will tag @Mixed flock enthusiast
and @R2elk for help. You may also post here on the guinea forum:
https://www.backyardchickens.com/forums/guinea-fowl.45/