I would still start treatment of coccidiosis with Corid (amprollium, Amprol) in the cattle section of your feed store while they are still doing well. Mix 2 tsp of the liquid or 1.5 tsp of the powder per gallon of water for 5 days as the only source of water. After finishing Corid, give several days of vitamins and probiotics to get the intestinal bacteria back up to speed. Here is a link to read: http://www.the-chicken-chick.com/2012/12/coccidiosis-what-backyard-chicken.html
X2. Start treating with Corid asap. If you wait until you see more or worse symptoms the more chicks you will loose. This is easily treated now but the longer you wait the more damage they get and the harder it gets to save them.