Get some liquid Sulmet NOW! If she won't drink it, add a bit of sugar to the water to entice her. Sulmet works fast for Cocci. Most feedstores carry it for about $10 a bottle. Corid is also for Cocci, but it works much slower and given your description of your hen, you probably don't have time to wait on Corid right now. Blood in her droppings means Cocci. If you don't treat her immediately, she will die.