I used to vomit a lot after my adrenals came out - it was the weather. I used acupunture... but still, we need more info to even comment. I still have no idea why on mine.
I echo Rumpled. Need more info. What has the doctor said up to this point? When I forget to take my hydrocortisone I get very nauseous. My cortisol is low because of Pituitary surgery.
Horselip
He may have CF leak (Spinal Fluid) ask hi if he feels better when he lays down.
What kind of tumor? Was it near an ear or pituitary where the vomiting is a physical or hormonal reflex?
What kind of tests have been done as a follow up? Other scans, hormone tests, tilt table, etc?
Does he vomit once, all day?
Can you give more information?