thanks for the query,
as you say he is hypertensive, is he on medications because the medications can always cause low bp
as a sideeffect so i think it would be better if you just got his bp checked regularly at home or at his doctor's place and as for the stroke
is concerned it might be a sign of an ischaemic stroke as a haemorrhagic stroke would have had high bp
after the incident since he is hypertensive it would be better if you get a ct brain or an mri
just to rule it out if you can afford it. because it might be a transient ischaemic attack also.take care.