Thanks for asking the query,
Bump inside the mouth can be a canker sore
or an ulcer.
Bump on the roof of the mouth which is painless can also be an minor salivary gland
It can also formed by an infected tooth which is draining its abscess in the area.
Other than this it can be due to vitamin B12 deficiencies , tobacco use, smoking, low immunity, bacterial and viral infections.
I would suggest you to visit to Dentist
and get a checkup done, take x-rays if needed.
Aviod eating of hot and spicy foodstuffs for some days.
Maintain a good oral hygiene
, yake lukewarm saline gargles, antiseptic mouthwash gargles to prevent infections and promote healing.
Hope this helps out.