Well some of my hens aren't laying right now, so don't feel like your the only one, yours is bound to lay soon. It depends where you live also, and if their coop is well shaded.
During spring and summer when the days are longer, they'll lay more. But since winter days are short, and if its...
Is she starting to molt? Around this time they aren't laying because they are either molting or growing their feathers in.
If they've been in their coop for a while and it's wet, there's a higher chance of them getting worms or Cocidiosis.
Signs of worms is runny poops, which can lead...