My cat is lying in the litter box
by Ron C
(Wellford, SC USA)
My cat is lying in the litter box. Also she has a black line across the top of her nose, and is not interested in eating or drinking.
I'm sorry to hear that your cat is not feeling good. I'm not sure what the black line is, but the other things you mentioned would concern me.
In my experience, cats often lie down in the litter box when they're stressed or ill.
Your cat is also exhibiting two more signs of stress or illness... not eating and not drinking.
If she were my cat, I would call my vet as soon as possible. Most vets I've dealt with say if your cat is showing signs of illness and refuses to eat or drink, it's time to get medical help.
I hope that helps and I hope your vet can help her heal quickly.