hi and welcome to HCM,
After reading your symptoms i suspect your have developed fungal infection
of yeast caused by candida albicans knows as oral candidiasis
It is caused due to dry mouth conditions or xerostomia
, long term use of certain antibiotics ,poor oral hygiene
i suggest you to apply topical nystatin or ketokenazole oral ointment , maintain good oral hygiene by oral rinsing with lukewarm saline water.
use of cholrhexidine gluconate mouthwash is NOT RECOMMENDED here.
flucanazole tablets 150mg once daily will help in subsiding symptoms.
drink lot of water and keep yourself hydrated.
i hope this helps,