I wouldn't want to know a company when, how often and which doctors I consult for one. If you don't want to share your search history you may not want to share your location data either. I would see these as equivalent.
Depends. A lot of doctor's offices are in "medical parks," so it's entirely possible they don't know which doctor you are seeing or why. They have easier access to that information via your calendar (if you use it) than your location.
For that matter, your location data couldn't be proven to be yours on merit alone. Anyone can be using my car, and anyone can have my phone, at any given time.