missT,
I do believe it is related to CF. It's interesting that you post this now as I have only been reading about the connection to CF this week. CF is a disease of the excretory glands. The parotid excretes saliva.
I have had pain and occasional swelling of the glands under my jaw bones for many years. Doctors would palpate and then shrug their shoulders. I've had mono multiple times so I figured it was leftover from all that glandular swelling. I'll try to retrace my steps of the online articles I found and get back to you.
I hope the tumor turns out to be nothing!!
Joan