Is she pumping her tail at all? Take a look at her vent; is it talking to you like she wants to expel something?
My gut feeling is a reproductive problem, based on the two shell less eggs, cessation in laying, weight loss and body language. The poop may be from lack of appetite. Can you also get a fecal float done? Can you check them in the coop at night for mites? Or are you keeping her in? Can you bring in her best friend, too, to keep her company? That might pique her appetite.
The two “weird” eggs... were they solid or just regular liquid egg material with a membrane? Do you know if they broke before she got them out? Raw egg in the reproductive tract can cause salpingitis. If she were mine, I’d seriously consider hitting her hard with enrofloxacin. Is an avian vet an option for you?