Thanks for writing to us.
The white spot at the back of tongue can be due to Depapillation due to throat infection
,tobacco or pan chewing.
I would advice you to gargle frequently with lukewarm saline.
Usually in such cases,Amoxycillin
as well as analgesics has to be administered.
Vitamin B complex as well as iron supplements
has to be administered.
Avoid spicy allergic foods.
Hope this helps.