Thanks for posting your query.
With the available described symtoms, there appears to be possibility of impaired immune system with persistence of herpes zoster
Impaired immune system may be due to systemic involvement like kidney/liver disease, diabetes, AIDS, chemo and radiotherapy, during menses, sun exposure.
Possibility of impaired immune system is suggested by weight loss
You should consult with internal medicine specialist and should go for thorough check up.
You should take antiviral
oral medications and apply loacl anaesthetic oral paste for better oral intake.
You should also apply glycerine which helps in oral intake.
, vitamin C rich supplements.
Dr. Mayank Bhargava