Weird bump on my silkie's tummy

Hi!

So I just noticed a weird bump on my silkie's tummy. She's roughy 2 YO and is healthy.
It's a bit red and painless. She just stopped taking care of chicks after 2 months of brooding.
She's living inside full time, is parasite free and healthy. I noticed it because I was petting her, not because of behavior change.
What could it be? A kyste? Can chickens have ingrown feathers?