Hi.. Thanks for the query.. As per your complain and presentation of symptoms a small white lump formed beside canker sore is not probably cancer but it can be another canker sore that has not yet ruptured into an ulcer.. To me it seems most probably to be either an irritational fibroma caused either due to injury by some sharp edge of tooth or tongue bite or it can be an inflammatory lump caused as a result of inflammation or it can be an initial phase of canker sore that would ulcerate in a day or two or can also start healing without ulcerating.. Nothing to worry just do warm saline gargles. Gargles with cold water and sucking ice pops can also help.. Take a multivitamin tablet for one month.. Avoid hot and spicy food.. In case of pain you can apply a numbing gel containing Lignocaine over the ulcer as well as the lump.. Hope this helps.. Thanks and regards..