Hello, Thanks for posting your query. Area of Lower lip, chin and tongue is supplied by facial nerve. Any irritation, viral infection and compression can cause numbness and tingling in these areas. However, like your doctor said it can also be due to herpes zoster (shingles). Usually shingles present with pain and rashes but it may present differently. Normally it is treated with antivirals (acyclovir) and steroid (prednisone). It may take few weeks to few month to resolve these conditions. Sometimes anti-depressants and anti-consultants may be used. You should continue your treatment and hope for better. Hope it helps. Take Care!