Sick duck. Please help!

[faithandfeathers]

My Pekin is shaking and doesn't want to get up. Her eyes look like she's not feeling well. I don't have any idea what's wrong or how to help.

 

[faithandfeathers]

More pics

 

[faithandfeathers]

I put her in a tub as a hospital. More symptoms for your consideration: she laid an egg, but it had a soft shell. All I found was this crumpled mess and the rest was mashed into her towel. She also has pretty dark poop. She was outside the day before yesterday, so that may be from something she ate or it could be a symptom. This one was pretty runny too.

 

[faithandfeathers]

Local vet thinks that she has calcium deficiency, so I have started giving her calcium and vitamin D supplements. My concern is that she doesn't seem to be eating. Is there anything I can do about that? And how long would you think it should take for her to start feeling better? We are on day 4 of supplements.