The findings that you mention suggest either:
Increased intracranial pressure -- if the diplopia is from an apparent bilateral or unilateral 6th nerve palsy with horizonal double vision
Chronic Basilar meningitis
which is picking off one or more cranial nerves. TB?
I would scan with contrast paying attention to the meninges.
If you don't think its infectious, also consider Wernicke's syndrome from thiamine deficiency
I don't have any experience with Cerebral malaria
, but understood it had a more encephalopathic picture due to its diffuse vasculitic nature.