The presetation of brain tumour usually starts with intense headache, vomiting without apprent cause, dizzyness blurring vision double vision change of personality weakness of the limbs and so on.The symtoms varies according to the position of the tumour in the brain. There some standered test are done. X-Ray of the skull, MRI Scan, EEG, CSF examination blood tests for hormonal level and angiogram of cerebral arteries. You need to see your doctor who will refer you to neurologist if necessary. Please remember not all brain tumours are fetal many of them cae curerable with surgery.

Feeling sick with dizzy spells and tinnitus(ear sizzling)are pointing to an ear(nervus accusticus )problem not to an brain tumor.You need an ENT doctor and testing.Try Betahiste(betaserc) 3 times 16mg. The origin of this need to be clarified by a clear history.I refer for differential diagnosis to :the tinnitus flowchart on the net.
I cannot explain your eye problems although frequently seen with balance problems.