Hi.. Welcome to HEALTHCARE MAGIC.. I have gone through your query and can understand your concerns.. As per your complain Radiotherapy used to kill cancer cells also kills the normal body cells along with cancer cells causing severe ulceration in the mouth.. If now the radiation exposure is stopped the mucosa will gradually heal but take a long time to resolve... In 5 days you can expect only minimal healing and the medication you are taking is to heal fungal infection that is oral thrush.. For oral ulcers you should start gargling with numbing mouthwash containing Lignocaine to relieve pain during chewing, eating etc.. You should apply steroid ointment over the sores.. Start taking Vitamin B complex supplements.. You should suck ice chips for reducing inflammation and pain.. Maintain a good oral hygiene to reduce infection and in case if brushing is painful get soft oral swabs prescribed by an Oral Physician that will help in maintaining good oral hygiene.. You can also talk about advising a drug known as Palifermin that will help in repairing oral mucosa and healing ulcer faster.. You can use a straw to drink liquids.. Take a soft and bland diet and avoid hard , sharp and spicy foods.. Hope this information helps.. Thanks and regards. Dr.Honey Nandwani Arora.