Licking and chewing on her paws is a sign of stress. Can you think of any changes in her environment or daily routine that could be causing stress? I have seen this occur when a new dog is introduced. Have you moved to a new house or something significant like that recently? I'm not a vet, but I got this information from a vet.
I have seen it turn into a viscious cycle rather quickly. I.e., the dog licks to the point of making the hair come off, creating a raw, sore spot, then she licks the raw sore spot, which gets infected, and it's hard to break the cycle.
Pet stores sell a green-apple-tasting spray for the purpose of deterring the licking. There are also "over-the-counter" stress relieving homeopathic products available online (search from google.com). I have no experience with them so don't know how much they help.
The fact that she's also scratching her ears make me wonder if she has allergies (yep - dogs get 'em too). Maybe it's the allergic reaction to -- whatever -- that's causing the stress, that's causing the licking?
Best wishes, hope this helps.