Thanks for asking the query,
Lump on the roof of the mouth is because of reaction to the trauma caused 2-3 days back .
it can also be because of blockage in the minor salivary gland or vessicle .
Visit the dentist
and get the checkup done .
Apply dologel or mucopain over the affected area .
Use saline water gargles 3-4 times daily .
Hope this helps out .