Kim,
Welcome to the sadistic world of LC. You will now view everything through the lens of lung cancer. I was aparayzed with fear when mom has swelling in her abdomen, sure it was liver mets. Nope, just a side effect from radiation. Then when here vision blurred I was sure the cancer was in her brain. Nope, just the opthamalic migranes she has had for years.
If the nausea is something your mom was experiencing before the LC, most likely it is not from a brain met. And the description is consistend with Sundown Syndrome. It's always best to rule out what you are afraid of, but it isn't always the cancer causing problems.
Susan
ps--And we who live in LC word with you will appreciate that only cancer could make you treat an Alzhiemers Dx as good news..