That is lash material. If vet care is not an option (they can test to see which antibiotic might be most effective) then I would try Baytril (enrofloxacin). You can get it without prescription at pigeon suppliers : https://jedds.com/products/enrofloxacin-10?_pos=1&_sid=a3e74bb01&_ss=r
No...
It does appear to be lash material, if you still have it, cut it open and look inside, that will tell for sure. It's probably the cause of the prolapse, and there may still be more material inside. Does her abdomen feel bloated?
Here is more on salpingitis, the cause of lash material...
Pictures of the prolapse would be helpful, and if you have what you thought was lash material, pictures of that also.
Keeping it moist is the most important thing, don't let it dry out.
Sometimes you have to hold it in for quite a while for it to stay, and it often comes back out when they...