It often takes them 7-10 days to get over an attack of vestibular disease. Its terribly distressing to see but it usually is not fatal.
As it appears to have been triggered by an ear infection I'd get that cleared up and check him for a thyroid problem and consider changing his food to a low allergen likely diet such as Wellness fish or rabbit or venison as often food allergies (even to foods they always ate) will trigger ear infections. Thyroid issues often lead to allergy issues and are really common in labs.
You can read about vestibular disease here
www.marvistavet.com/html/body_vestibular_disease.html
Looks like vivitonin is a UK pet med.
http://www.intervet.co.uk/products_public/vivitonin/010_overview.asp
It may be available to your vet as propentofylline.
For home care for a dog with mobility issues check out the ideas at
www.handicappedpets.com
Hope this helps you!
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