in-grown feather?

i was just wondering if in-grown feathers is a common problem.

i was checking over one of my girls and she had what looked  like a huge pimple with an open black hole. i put a little pressure around it and a sticky, greasy feather came out. i had to pull most of it out gently and when i i pressed again lots and lots of dry puss came out. i drained it entirely and then washed with diluted dettol before spraying with purple spray.

do i need to do anything else? she's fine - broody but ok otherwise.

When my goldtop, Grace, was not very well, I took her to the vet and she found a lump on her back.  Said it could be a feather cyst or tumour.  Within a few days the chicken's back was covered in lumps.  I did everything I could with antibiotics and sprays but it must have been tumours as she didn't survive.  Luckily, you chicken sound as if she has a feather cyst.  Just keep it clean and watch the other girls don't peck her.

That can happen with humans, too - I knew a teenager who had to have an in-growing hair cut out of his back but it didn't recur.