You should move – if not hierarchical – to “post_tags”, or a custom non-hierarchical taxonomy.
The rest is more a query Question:
- New template > Query taxonomy > Add specific tags to the query
- Assign template to page
- Add page to menu
So if you link to london and want to display all doctors, including location and specialization, Query for the taxonomy “city” > “london” and add tags “location” and “speziality”.