2 week old chick

So i have 3 chicks and one has been having slightly odd poops and seems sick. It had really light tan poops and now just had really bad diarrhea with some mucus on my hand. They are on unmedicated feed and im concerned about coccidiosis. I can pick up meds tomorrow but im not even sure if thats...

I have a 12 day old chick who i’ve been kind of suspecting is a rooster based on his behavior. But of course, only time will tell. Today, I heard a weird noise coming from the brooder, so I went to check it out because it sounded like maybe a chick was getting pecked? But once I got over...