Do you think it is feather picking or lack of protein in the afflicted pullets?I'd cut out everything but the cheese and mealworms for a couple days. They need a total of 16% protein. The scratch and everything but the cheese and worms are pulling that down. Even BOSS is less if it still has the hulls on.
The layer pellets are balanced and even though you're providing a good combination of things, my thought is that you're cutting the protein.
For an inexpensive quick fix, canned mackerel has all the amino acids and is cheap per ounce.