1 week old chick - mass in abdomen

[Ahavati]

We have 11 chicks currently in this batch (lost 4) and I noticed today that one has a strange hard mass feeling in her lower abdomen. Down where I assume her pelvic bones would be. I checked the other chicks and they don't have that. When I turn her on hr back to inspect, you can see the lump in her entire bottom abdomen. No sides of pasty butt or anything. She acts normal. Is this something that needs immediate attention?

 

[JuliaWesterbeek]

I would separate her from the rest just in case it is something medical and it can spread to the other chicks. Observe her and if she completely acts normal but her together with the other ones.

Did all the dead chicks have the same lump, cause if they did that would probably be the reason for their death