welcome to HCM,
as per the details u have submitted, the cause of the headache is more towards vascular and propably it is a TEMPORAL ARTERITIS
.. so he has started wysolone
.. but the wysolone belongs to gluco corticoid family and increase in B.P is rare ...steroids
with excessive mineralocorcoid action will have fluid retention and that leads to increase in B.P..
so we cannot attribute wysolone will be the cause for raise in B.P ..its propably due to increased pain towards the end of the day and not having round the clock control of B.P
so i advise you to add on AMLODIPINE
5MG in the night time...it will take care of the raised B.P..