Lump @ base of head

[Quad A]

We have 9 Partridge Rock chicks that are 5 wks old - 2 of these each have a lump @ the base of their head/neck and since this is our first time raising chicks we could use some help in ID'ing the problem/treatment. The lumps are approx 1 inch in diameter, flesh colored (not red or broken open) and are without feathers. The chicks themselves are acting fine - eating, drinking, pooping, not lethargic. Should they be quarantined from the other 7?

 

[gdrake_man]

Is the lump hard or soft?

 

[Quad A]

The lumps are soft - the chicks don't appear to be in any discomfort when we touch them...