They could just not be feeling well for some reason. I’ve had many chicks over the years that acted sickly a few days then were fine the next, like they had a cold. I would just keep an eye on them and update us if you want :thumbsup
It doesn’t look like cocci to me. Maybe give your chicks some probiotic mix in their water or you can mix a little bit of apple cider vinegar in their water! It’s healthy for chickens and contains good bacteria :)