We have 3 older girls that are about 4-5 years old. They have all been doing pretty good so far but latley I have been concerned about Cloud, our White Roc hen. Recently, I noticed that her comb has flopped, which I know can be normal for older chickens. She has also never been afraid of being an outlier of the flock sometimes too, (like she doesnt feel like she has to stay close to the others.) But she has also been lagging behind more than usual. She has been sitting down a lot more than usual, away from the others. She has also never really liked to be touched that much, but when she has been sitting down, she doesnt respond like normal (her normal is usually just walking away.) I have also noticed a bit more dihharia (or watery poop) than normal too. She has still been walking around sometimes too, and from what I have observed, she has also been eating. She is just acting kind of strange.
Should I be worried about this, or just let her be? Is it normal for older chickens to be like this?
Here are some pictures of her.