Joe,
You are correct to not share what you have read yet with your mother. A recurring theme with potential diagnosis and biopsies on this site and in all cancer forums is "Until the doctors tell you it's cancer it's not".
You are human and we all even myself act human. We get scared and feard the unknown and expect the worst. ( Read my post in the General Board entitled "Friday Sucked...").
I'm not trying to passify or belittle your concern. I'm just trying to help guide you through the process a little bit.
For you: Be positive, support your mother, tell her you love her and are there for her. Laugh with your mother. It'll make both of you feel better and it does re-energize you.
In my opinion what you describe could be a multitude of afflictions and most of these are not life threatening. Without pictures, blood work and x-rays I obviously cannot begin to steer you toward an accurate diagnosis.
I can however, answer most of your questions before and after diagnosis as they are related to the mouth. I can be a shoulder for you to lean on and if you desire, give advice to about the issues revolving around any condition and treatment of the condition when the mouth is involved.
E-mail me anytime.
My thoughts and prayers will be with you and your mother.

Stay strong for your mother.

"..when you look in a horse barn look for horses... not zebras. If and when you see a zebra deal with it at that time." Annals of Medical Pathology.

Cheers,

Mike