hi and welcome to HCM,
Shingles is the viral infection caused by Herpes virus, as you are confirmed of suffering from the herpes infection, Pain in the back tooth can be related to it. but this can be confirmed only by clinical examination by a dentist
and x ray evaluation, accordingly treatment can be carried out.
you must be on antiviral
therapy. Along with medicines i would suggest you to maintain good oral hygiene
by using antiseptic mouthwashes like betadine or chlorhexidine
to prevent infection of other oral tissues, pain in the last tooth can be due to gum infection
Drink lot of water and keep yourself hydrated.
i hope this helps,