Normal poop is good! No evidence of blood in any droppings (coccidia is what always pops into my head when I think of sick chicks...as well as pasty butt for the tinies). And if he/she is eating a bit - that's good too!!
Knock on wood, but in seven years I've only lost one chick, and I have no idea why it died (was dead when I found it after being active and happy just hours earlier). So my knowledge of sick chicks is very limited.
Do you just have a few chicks, or many? I'm wondering whether it could have gotten run over by rougher youngsters? If I was in your shoes, I'd probably just baby it for a day or so (scrambled egg, electrolytes) and keep an eye on it. If others are rough housing quite a bit, then I'd either separate the weak one, or put a wire divider in the brooder so it could see the others, but not be involved in the running/jumping, etc. I do keep VetRX on hand here, so I would also give a bit of that.
I hope your chick pulls out of whatever is ailing it...