Hi,
Been away from the computer all day . . .
TD, you're doing very well. Those do appear to perhaps be some dried poop - now whether they are attached to tissue or feathers, - the one on the left in the photo appears to be attached to tissue. Elfie, who's not a big swimmer, had some dried poop dangles pretty tightly attached to her vent a couple of years ago - even caused some bleeding when she laid an egg - that's what got my attention.
When Sechs was first eggbound/prolapsed,(edit - after the vet removed the egg and put some stitches in her vent) I kept her in a darkened but not pitch black room, and there were eggs there, and she gathered them up and started sitting...which was great because mine don't lay when they set eggs...
Reducing inflammation is important as you know - I suspect the PrepH can help topically - and I would start adding turmeric to her food right away. It's a natural anti inflammatory and the vet told me it is fine to give to ducks until you can get to a vet.
....
edit to add
Since not all vets think the same way, I will report what I recall from Sechs' second eggbound episode. This time she was not prolapsed yet - I found her straining, not looking right. Took her in, the x-ray showed the bound, lightly-shelled egg in her oviduct. She was given a hormone injection to stop egg laying for a month, some calcium, and we started her on Metacam anti inflammatory and Bactrim antibiotic, as she was already showing signs of some beginnings of infection. Kept her on the Metacam for several days, and the Bactrim for I think 12 or 14 days (I suspect I posted about that). With the hormone injection no need to keep her in the dark. Took 5 or 6 days to pass the shell - the yolk and white came out before then.
For Casey, keeping her clean as possible, lubricated, and TLC'd till you can get to the vet tomorrow makes sense to me. I would definitely add the turmeric to her food or water. You know that stuff stains, right? But I think it is helpful. And ought not interfere with anything the vet does or prescribes, I think.