Your symptoms are suggesting as if you are having recurrent bouts of transient ischemia of brain called as transient ischemic attacks ( TIA).
A TIA may cause sudden dimming of vision,slurred speech,mental confusion
,loss of balance.
This happens only for few seconds or minutes and then person recovers completely.
Other causes which can cause similar symptoms are
Hypoglycemic attacks in a diabetic
Partial seizures of brain
Brain tumors etc.
You must consult a neurologist
as having a TIA is a risk factor for future major stroke.
You must get a CT or MRI brain,neck ultrasound