Chicken losing feathers

[NH_Chicks_And_Guineas]

Hello,
Our 17 week old chicken is losing feathers. It keeps digging and lying on the ground. Another chicken keeps following it and lays down with it while and kind of nudges it over. I saw a couple Guineas and Chickens picking at the area. Should I be concerned. I'm new to this. First flock. Had them since 1 day old. I attached a pic of it laying down and standing up.

Thank you for your help

 

[Wyorp Rock]

Looks like they are dust bathing.
The feather loss is likely due to finishing up molt since she's young, but it's always a good idea to inspect her to see if there's lice/mites and of course new feathers coming in to replace those that are lost.