Thanks everyone. I have used a bearing retainer on another ewe before and it was only so-so. Also, Purl's breeder said they only had one ewe prolapse before, and they used a retainer and the next day she was dead and had a prolapse the size of a basketball (when the day before it was only the size of a tennis ball or so). In my experience, the ewe feels the retainer and constantly strains against it. I will definitely order one, but if Purl prolapses again after lambing (which hopefully she will not), I'll have the vet out again to suture her so I know it won't happen again. I think the bearing retainer will be useful in case it happens next year, and hopefully I would catch it early on.
I know "they" say it can happen again, but I plan on breeding Purl again next year if all goes well this year. She's young and I'm thinking it was just a fluke. She may be a *tad* overconditioned, though she's definitely far from obese, so next year I'll be extremely careful with nutrition and management and make sure it wasn't my fault she prolapsed. Since none of her relatives have ever prolapsed (and they have a LOT of her relatives) I'm thinking it's not genetic and is just a fluke.
Luckily the vet didn't have to go very far inside, and everything was extremely clean so I'm going to hold off on antibiotics for the moment. I'll watch her and the moment anything seems off I'll make sure to treat her.
I'm not worried about her lambing. I've ton lots of experience positioning lambs and other critters, so I feel confident I can handle that.

I just want it to happen soon so the pressure is off her. Plus, she's due NOW and I don't want those lambs to get too big!