Corgi grooming--help?

I have two lovely corgis, one who is two years old and the other who is just four months. The elder is a 'close coat' which basically means she doesn't have an undercoat or the characteristic "fluffy pants". She also has a natural tail which keeps her rear end free from debris.

Our puppy is much different. She is a regular undercoated corgi but she is a natural bobtail, which means she was born with no tail. This lack of tail and the presence of the "fluffy pants" means that a lot of fecal matter gets retained around the anus. She's constantly trying to scratch her backside and appears to be in great discomfort. A recent bath revealed that dried fecal matter has actually resulted in hair loss and irritation on her backside.

Seeing on how our other corgi requires very little maintenance, I'm unfamiliar with how to deal with this situation. Do we need to take her in for regular grooming in that area? Does her fur need to be clipped a certain way? How can we help bring this little dog some relief?