Yes, it’s meant for days or weeks but not months of use.
Not only are their risks wrt to blocking compensation, but it also puts you more at risk of some pretty nasty brain disorders if used chronically, I understand, including Parkinsonism.
You could have considered Amitriptyline instead of both of these which itself has pretty effective vestibular suppressive effects but can be taken chronically.
Perhaps you could go easy on the Stemetil and see how you go with Nori.
The biggest issue is that you will probably find it hard to judge how much the Nori is helping you whilst under the influence of the other drug.