Sometime we forget that brain tumor patients do get unrelated problems. It is not always due to the tumor! Sometimes the positioning of your head during the surgery can trigger Paroxysmal Positional Vertigo and there is a really simple fix for most cases. You need to see an ENT doctor who can do a simple manuveur which cures it in some cases. Obviously talk to the neurosurgeon first to see if they think you are healed enough from the surgery to have the manuveur!