Thanks for the tag
@Wyorp Rock
Hi there!
I've found the best thing for helping adult poopy butt is to get into a routine of probiotics. Whether it's powdered in their water, Greek sugar-free yogurt, or fermenting grains...about once or twice a week will help their guts and digestive systems.
Silkies are prone to about everything more than most breeds, so I've made a habit of giving them half a dosage of Rooster Booster granules in their feed, which they've been on for eight years now. Once one had a cold (respiratory infection), but other than that, nothing but an occasional poopy butt. Sometimes the poopy butt isn't them; it's their feathers, so I use kitchen scissors and cut around their butt. I do their eyes first, though.

The one that had the cold was in here for a week, and putting her back out only excited the roosters as she was in one of our breeding pens. I stood out there for a few minutes until they calmed down.
As far as temperatures go, they were out today when it was 13F and a feels like temp of 4F. That's a little too cold for me to let them out usually, but the sun was actually out today, so I did. They have an attached covered area to stay out of the wind, which they used for about 2 minutes, then out they went.
Their coop is heated to 40F, mostly for me, so their water and eggs don't freeze, but also for them when it gets frigid cold here. Today, I noticed them heading into the coop a couple of times to warm up, and then back out they came.
You might have found out already that they like wide flat perches, don't fly for beans, and can't jump well either. We have ladders for them to get up to the nest boxes, and some sleep on top of those or on the railing in front or in the boxes themselves. I put horse bedding pellets in the nest boxes so they're easier to keep clean than straw being pooped on.
If you have any silkie questions, I'm happy to try to answer them. I hope she's back to normal now.