A family member who is in his mid-70s has had a swollen lump under their jaw since early February. It appeared suddenly, and after a couple days, went down in size a bit. He got antibiotics, and the swelling slowly went down a little more. After a month or so, it was still there and while waiting to see the GP, used a warm compress at night. The lump would more or less disappear by morning, and then swell up a bit by evening but did get smaller, just never went away and never got any bigger. Not painful, and its hard. The doctor thought it could be reactive lymph node, but absolutely no other symptoms, no illness, etc.
Fast forward to now, which is why I'm so worried and I think he's not telling me the full story. Whatever it is will be diagnosed soon as after an xray and CT scan, he's been scheduled next week for a biopsy. The swelling is still there but only a little bit bigger than the normal-sized gland on the other side of the jaw. The CT scan found a 'mass' either next to or deeper under his jaw (its not visible and can't be felt). Of course, I worry it's cancer either spread to the lymph node from head or neck, or from elsewhere.
Would a cancerous mass cause this sort of rapid swelling, and then slow decrease in size, and then more or less disappear after using a warm compress only to keep coming back but continue to slowly get smaller (but not back to normal size)? The biopsy results will confirm if its cancer but I'm just so anxious and worried.