If she is sick she might need heat, but I always use an inexpensive thermometer under the heat lamp to know what the hottest spot is. Clean off the poop as needed, since they do get poopy. Make sure they have a cooler spot in the brooder to get to, or enlarge your brooder. The Corid should be...
Can you get some Corid right away at your feed store? Get the liquid if you can to treat for coccidiosis. Give a couple of drops of the undiluted Corid into her beak now and again in the morning. Dosage is 2 tsp of the liquid Corid in each gallon of water for 5-7 days. Treat all of your chicks...