Poop shouldn’t be sticking to her bottom, if it’s mushy enough to get stuck in her fur you may need to look at adjusting her diet.
Before that though, you can try to clip her fur down there for the time being, however you need to be extremely careful that you don’t nick the skin. You can give her a little butt bath, 1cm of water in a dish to splash water on the area to clean it up, however you need to be careful not to cause more irritation. I’m not sure what to put on the skin in that area to help soothe it.
In regards to the mushy poop, is she eating lots of hay? Grass hay is the most important part of their diet and is the best thing for getting poops nice and solid and round, mushy poops are frequently caused by too many pellets, too many greens/veggies, too many treats, poor quality pellets etc. If you can get to the root of the problem, you won’t have more issues with the poop getting stuck in her fur. 