Thanks for the advice everyone. I double checked all cats for fleas again and didn't find any. I also double checked all of my cats bottoms and found nothing. Sky has been sleeping under my bed so I don't want to disturb him. I'll call my vet tomorrow morning and will hopefully be able to bring Sky in some time tomorrow. If I have to treat all of my cats, I'm going to have trouble with Cirrus because I haven't been able to pill him in the past. He's also very difficult to get into a carrier. I sure hope that the vet says that this isn't contagious. I've also noticed that Sky's tummy is big and round and bloated looking so maybe it is roundworms.