Hi! For about 2 months I have had this bump on my gum against a tooth that I had a root canal on 2 years ago. It does not hurt at all. It will fill up and get big and I will push on it, and it will pop and pus and some blood comes out. It then shrinks down for about a week and a half then fills up again until I pop it. I went to my dentist, and he did xrays on the tooth but found no infection on xray. However, the bump wasn't filled up when he did the xray. He said he really didn't know what was causing it and prescribed me antibiotics for 7 days. I took all 7 days (finished it today), but it is still there. It has not filled up again, but the bump is still visible (flat and whitish). After reading other posts, is this a fistula? I am so scared I have oral cancer, though my dentist assured me it was not because oral cancer wouldn't have a sore that has pus that fills up and then goes down. Is this true? Why didn't he see an infection on the xray if it is an infection? I have an appointment with an oral surgeon to look at it, but that isn't for another week. Please help. So scared it is cancer.