What your are describing can definitely be symptoms of brain mets. Depending on the area of the brain effected you could expect to see many different symptoms. A few weeks ago we found my mother also had brain mets with absolutely no symptoms other than dizziness. I'm surprised the oncologist did not reveal results of the MRI... or perhaps he did and your father isn't telling you???
My mom had three lesions and received stereotactic radiosurgery (gamma knive). It is a one time intense radiation zap to the lesions only and is done on an outpatient basis. She also has mets to lungs and bones.
If you dad has a problem telling you directly about test results you can also ask if he would sign consent for you to just talk to his doctors directly. I make sure Mom signs consents wherever we go so I can also discuss her case with the doctors.
Best Wishes,
Texas Lil