Hi.. Welcome to HEALTHCARE MAGIC.. I have gone through your query and can understand your concerns.. As per your complain it does not seems like a Canker sore but looks like an Abscess caused due to bacterial infection leading to formation of a pus filled bump.. You should consult an Oral Physician and get evaluated and he can advise you oral intake of antibiotics like a combination of Sulphamethoxazole and Trimethorphan, anti-inflammatory painkiller like Ibuprofen.. Cleaning the area with antiseptic solution like Betadine and apply an antibiotic ointment over it.. You should gently press the are with a sterile gauze to release pus as it will help in healing faster.. In case if the bump forms again and again Incision and drainage can be done for relief.. Hope this information helps.. Thanks and regards. Dr.Honey Nandwani Arora.