Hen is droopy, just not herself

This certainly doesn't qualify as and "emergency" but I wanted to get input from you wise BYC folks on it.

My oldest gal, Marigold, just isn't her usual self lately. She keeps away from the flock, free ranging on her own. She stopped laying a month or so ago - and the color is gone from her legs. But her comb is lying over and losing color too. Her tail feathers seem not as long, the just look kinda rough and all her feathers feel sort of dry and bristly.

What really got my attention though is, I picked her up yesterday and she's lost weight. I felt her abdomen and she's not egg-bound, she's still eating and pooping - though I'd like to see her poop so I can get a good look at it (Gee, never thought I'd see the day that I went LOOKING for poop to examine!)

I'm not sure of her age, she was a hand-me-down hen that got my flock started last year in May. She's never molted since we got her, and only stopped laying over the winter (I didn't put a light on them). I would guess that she was 2 years old when we got her, so maybe 3 now. She's a production chicken, likely a Golden Comet.

I fed her a scrambled egg yesterday, and she ate most of it. I just can't figure out why the sudden change in behavior and the weight loss. Any ideas?