Statin is not for bp it’s for cholesterol so I assume you have another Ned for bo?
A sudden drop in bp can cause dizziness which is worse when on meds
One way is to get a home bp meter they are quite cheap so he can get an idea of how his body is doing…. It maybe he suffers white coat syndrome and gets higher bp at the doctors so doesn’t need treatment for that
I used to get the same when standing while on bp meds
But vertigo can do the same and apparently is more common with poorly controlled diabetes
I had it a bit last year and nearly fell a few times getting up or out of bed