Where to buy supplements for senior dog?

Hello po! My dog is suspected to have arthritis. Nagssqueal siya in pain when he gets up suddenly or pag mali ang pag tayo niya. We have done CBC, blood chem and Xray and all of the results were normal. So our vet has suggested to try mobility supplements. Ito ang nireseta samin:

Himalaya Mobility Plus Royal Canin Advance Mobility Support

I have been messaging vets and big pet hospitals around Marikina, Antipolo, QC, Makati and Taguig pero no luck. Anyone po na may idea kung san pa po pwede makapag tanong?