Hi..
Thanks for the query..
As per your complain sores in mouth and lips can be due to apthous stomatitis leading to apthous ulcers and in case if you are presently getting the
radiation treatment done, it can be the most probable cause for it..
Secondly yellow white appearrence of the back of throat can be due to improper maintenance of hygiene,
throat infection..
In case if you are told it can be yeast, I would like to explain that yeast infection or thrush is generally in the form of thick cheesy or curdy white patches..
So for cofirmation you need to get a microscopy of the scraping from the coating done..
In case if it is not due to yeast infection then maintaining a good hygiene and by gargling with 1:1 solution of
hydrogen peroxide and water and warm saline gargles with help in resolution..
For yeast infection Nystatin mouthwash,
clotrimazole lozenges and
oral antifungal medicines like Clotrim zole will be advised..
For mouth ulcers take vitamin B complex tablets, do warm saline gargles, betadine gargles and avoid spicy foods..
Hope this information helps..
Thanks and regards.