21 year old son has been fainting with eyes wide open and set. (very scary) he had stage 3 melanomia 2 years ago. cemo caused pituitary gland to swell?

Neurologist: He may be having atonic seizures and there would be concern about metastases to brain. It is urgent that he be seen by a neurologist for these spells for diagnosis and treatment. The neurologist would work in concert with the oncologist.

Fainting?: Possibly or seizures. Have him evaluated by his physician asap

Get this diagnosed: Based upon information provided, I suspect he is having seizures and likely should be placed on anti-epileptic medications. Contact the doctors, and likely have a neurologist get involved.