Hi.. Can understand your concern.. As per your complain the symptoms you explain suggest that the lump on the gums can be due to an infected tooth that could have become dead due to infection causing the nerves and blood vessels to get necrosis which leads to no pain in tooth but the infection could have progressed below the root tips of infected tooth leading to pus formation (DENTAL ABSCESS) as a result of inflammation and causing swelling.. The other cause can be some injury or infection in the gums, due to either any thing that got impacted into the gums or anything like some hard food item or a toothpick that injured the gums and carried infection along with it deeper into the tissues causing infection and swelling (GINGIVAL ABSCESS/ GUM BOIL).. These are the most common causes.. But to rule out the exact cause you need to get a clinical check up done by a dentist and get an x ray done so that it can be ruled out what is exactly causing you the lump.. In case of infected tooth root canal treatment along with antibiotics and painkillers can relieve.. In case of a gum boil professional cleaning of the gums along with antibiotics like Metronidazole and amoxicillin and painlillers for oral intake and topical application of gum paint can provide relief.. Hope your query is solved.. If you find the answer helpful please write a positive review and click on find this answer helpful as a token of appreciation.. Thanks and regards.. Dr.Honey Nandwani Arora.