I'm not sure what's wrong with my chickens. This is my second year raising them. Here's the deal. All my chickens have been fine, up until the last few days. First, I noticed one of them had diarrhea. Then, I noticed several of them had diarrhea. I just finished an isolation cage, so I isolated the sickest one. She's an Americana and has been laying consistently. The reason I say she's the sickest is because she was kind of drowsy looking, whereas she is normally alert. The rest of my chickens are still acting fine, except for the diarrhea and sneezing and congested breathing. I added three chickens two weeks ago, so I guess they could have brought it in. One of them was a golden-laced wyandotte and a pair of black-tailed japanese bantams. The bantams are fine. I also had a bantam cochin hatch two chicks three weeks ago, and I removed them from the flock two days ago. All of them except the bantams and the two chicks are eating layers pellets from my local feed store. Any help would be great. Oh yeah, I also have a silkie who has been laying on eggs for 15 days now.