Why does my hen run around really fast then sit down?
Lice are small straw colored insects. They will be all over. Mites are usually around the vent, but there are so many types that I don't know what they all look like.
To check for lice run your hand up her feathers (gently) the opposite way that they grow, lift up her wings, check her legs, her neck, and her tail. Mites lift up her tail so you can see the vent. If there is black that is mites. Any bugs around there are probably mites.
Also, if you feel itchy after holding her really close it is probably lice.
This just happened to my d'Uccle roo (who are prone to foot problems). Turns out one of his toes is bent under his foot. I'm not sure if it is broken but this happened to a chick once, but it worked itself out as she grew. I didn't ask if she had any problems with her feet, which I guess is an obvious question, don't know how I didn't think of that.