The information provided my you is not enough.i need
To know about your oral habits like smoking
chewing.these white lines could be any infected precancerous
white lesion like leucoplakia or lichen planus
.this even may
be aphthous ulcers
which get heal by it self in 5-6days.
I would advice you to consult an oral pathologist and get
a proper clinical diagnosis and biopsy
done.you can apply
hexagel or orobase for temperary relief.maintain oral hygiene
avoid hot and spicy food.