Hi XXXXXXXXXX~
Without being able to see your dogs in person, it's pretty much impossible to tell you why they're licking the way they do or what could possibly be causing it. The list of things it 'could be' is nearly endless: allergies, infestation of parasitic mites (mange), thyroid problems, or even bacterial or yeast infections are just a few. My suggestion is to call your regular vet in the morning and schedule an appointment for them to see your pups and see what they can determine. They'll most likely do a skin scraping of the affected areas (where they use the edge of a scalpel blade to gently scrape off the top layer of skin, looking for any mites), and possibly run some blood work to see if there is a thyroid issue. In the meantime, you can give a little liquid Benedryl at the dose of 1-2 mg per pound of body weight (meaning if your dog weighs 20 pounds, you can give 20 mg the first dose, and if that doesn't help, you can give 40 mg at the next dose) one time every 8-12 hours.
I hope this helps.
Certified Veterinary Technician
Associates Degree in Veterinary Technology. State and Nationally certified.