Thank you for your query,
Oral ulcers may be due to aphtous stomatitis
or due to stress
related ulcers which are associated with typhiod infection.
Rebamide is an gatric mucosa protectang and not cause mouth ulcers.
Give her multivitamin
supplemetation for 2 weeks and give balanced diet containing vegetables, green leafy vegetables and fruits.
Hope I have answered your query.