Coccidiosis is a top consideration. Only one or two of the 9-11 strains known to effect poultry *may* present as blood in the droppings.
Treatment with Corid is over the counter (walmart, TSC, other feed stores) or a prescription sulfa drug in the US.. Direct drench dosing to the beak will be required since off feed already. Also do NOT supplement vitamins during treatment with Corid (amprol) as it works by mimicking thiamine to starve out and slow the growth of the coccidia.. which are always present and only a problem in excess amounts.. often caused by warm humid conditions like those of a brooder.
Second considerations are crop blockage.. is it hard or full or squishy even though she isn't eating or drinking? Or is is flat as you would expect from a bird off feed?
While not usually seen this late.. also please make sure the vent (butt) is clear an not pasted over with droppings.
What are you currently feeding? Any reason to be considering malnutrition? Are you in the US?
Hope you chick recovers quickly!