I ate salami on roll with spicy mustard as eating a bump appeared on my gum line in back of mouth what can this be from?

Reaction or Trauma: Not easy to diagnosis with out evaluation could be a reaction or trauma to an item if it occurred in an acute stand point?

Bump: Could be from trauma, could be from irritation. How long is it there for? Give it a day and see how it goes, otherwise visit your dentist to see if something is trapped or if the bump is being caused by a problem from your tooth.