Duck with distended abdomen/prolapsed vent; calcium deficiency?

I have a 1.5-year-old Ancona duck who has a prolapsed vent and a distended abdomen. After a bit of research, I'm wondering if she's calcium deficient. I've never had any problems with egg shells, so I haven't been supplementing their layer feed with calcium, but now I'm thinking that wasn't the best idea. I can give her oyster shells in her feed, but I think maybe some oral calcium (this? http://www.fleetfarm.com/detail/aspen-calcium-gluconate-23-solution-500-ml/0000000001333) could help her get her calcium levels back up faster. Is a calcium gluconate 23% solution the correct thing to give her (sold for cattle)? Can I give it to her orally? I don't think I could give it to her as a shot, but don't want to hurt her by using it incorrectly or overdosing. What would be the proper oral dosage?

She does not seem to be in distress, or even sick - she has laid an egg each of the past three days, so she isn't really egg bound. Her abdomen is distended, though, and her vent has been prolapsing. I've been pushing it back in and treating it with hemorrhoidal cream for the past few days, and finally this afternoon it had stayed in for 18 hours, even after she'd laid an egg. I haven't checked her in a few hours, so I may be being over hopeful. But her abdomen is still distended, and I'm thinking her vent may prolapse again - so if the muscles are weak because of a calcium deficiency, I'd like to try to make sure that that is treated. Do you think the calcium gluconate might help?

Thank you!

 

I checked on her at 7 this evening and it still hadn't prolapsed again! Going to go check on her one last time before bed, but this is much better than she's been doing the past few days! Still has a distended abdomen, though. I added oyster shell to her feed this evening.

 

Still no more prolapse! I hope this keeps up!