Hard lump

[Ejlf]

I have a tooth that was due to have root canal treatment a while back due to many factors this never got done it has been fine for a while but flared up again recently only this time I discovered a honey lump around 2cm big at the very bottom of my gum below this tooth in between the gum and lip if you know what I mean the tooth has settled again and the lump doesn't hurt unless I push on it. I have an appointment in a week but I am just concerned can an abscess show itself this way? Thanks in advance for any help