Welcome to HEALTHCARE MAGIC..
I have gone through your query and can understand your concerns..
As per your complain mouth ulcers commonly occurs due to causes like nutritional deficiencies of iron and vitamin B12
, stress, acid reflux
imbalances, side effects of medicines etc..
As you have stage 4 kidney disease, there seems to be reduced immunity and resistence and it can be a cause for mouth ulcers..
I would suggest you to gargle with numbing mouthwash to relieve pain..
You can suck ice and gargle with cold water..
Do warm saline gargles..
Gargle with antiseptic mouthwash..
You should consult your treating Nephrologist
and only after his consent you can take Vitamin B complex supplements..
You should avoid spicy foods and take a soft and bland diet.
You should maintain a good oral hygiene
Hope this information helps..
Thanks and regards.
Dr.Honey Nandwani Arora..