Do you have actual license plate numbers that you KNOW match up with members on your care team? And depending on the make/model of the car, some models & makes are a whole lot more popular than others. And vehicles only come in so many certain standard colors...I know in my area, practically every 2nd or 3rd person owns a Ford F-150 truck, usually in white or black. Now, if I saw a Subaru following me in this area, it's be a little more suss as they tend to be a lot harder to find around here.

I'm sorry, I really do think it's paranoia. Mental health care workers do not drive around following patients unless you have multiple care workers who also happen to be stalkers.