Hi..
Welcome to HEALTHCARE MAGIC..
I have gone through your query in detail and can understand your concerns..
As per your complain biting of tongue can lead to ulceration and inflammation of tongue and this can cause pain but generally such biting is not generally so severe and extensive to reach the nerve and cause neurotic pain..
Pain which is occurring in the
electric shock like manner from chin to eye can be due to disturbances related to
trigeminal nerve leading to
Trigeminal neuralgia..
As it generally occurs after some triggers therefore there is a possibility that it is occurring due to chewing..
I would suggest you to consult an Oral Physician and get evaluated and a clinical examination of teeth will also be done as pain originating from any deeply decayed tooth can also cause bouts of
severe pain on chewing..
If
nerve pain is suspected MRI scan can be advised..
If there are ulcers on the tongue a biopsy will be helpful in diagnosis...
As of now she can take painkillers as advised and along with it for dry mouth suck tart candies.
Instil artificial saliva drops.
Gargle with specialised mouthwash like Biotene that is formulated especially for dry mouth patients..
Any further questions are welcome..
Regards..