Erin - like Victoria said, all that licking could be indicative of allergies. If that's the case, your mom should get that checked out soon. Growing up, we had a lhasa apso who was honestly the sweetest dog I've ever met - but the poor boy suffered from terrible allergies and would lick himself raw. Yes, we even had to have him wear the "cone of shame" for a while. He was absolutely miserable, and we would get the wet spots on the couch and chairs like you described. We ended up needing to put him on prednisone, which gave him a better quality of life for a while in some ways, but it had side effects (at first he was skin and bones, and then he got quite fat, among other things) and ultimately, it shortened his life a great deal.
I get really emotional thinking about it because he was just the most wonderful dog. I wish I had known about more natural treatments because I think we could have given him a longer, healthier life. We have a maltese-poodle-shih tzu mix and she's starting to show some of the same signs, so we're not messing around this time. We just started her on the Derma-IonX and I'm hopeful that it will help.
All of this long-winded reply is just to say that the licking might just be an annoyance now - before Frisket was diagnosed with allergies, we just thought it was annoying - but it could be something worse, so I highly recommend getting it checked out!