Thanks for reaching out about Phoenix. Pawing at the mouth is a common sign of nausea and low blood glucose in ferrets. This is often a problem in ferrets older than three years of age. There are multiple causes of low blood sugar including an insulinoma (pancreatic tumor producing too much insulin), intestinal malabsorption through the intestinal tract, not eating due to other problems (pain, dental disease, metabolic disorders, other) just to list a few. A veterinary visit is recommended to assess and provide a diagnostic/treatment plan. If this is an insulinoma, there are surgical and medical options to stabilize. For now, try offering a little Karo syrup of maple syrup to the gums and then encourage to eat the normal kibble.
Good luck.