Don't confuse a "doctor's aide/assistant" (whatever that may be), with the term "physician assistant" (usually seen abbreviated as "PA"), which at least in the US is a designated medical license, somewhat below the level of a full doctor, but requires more training than just an RN (registered nurse).
PA's aren't quite full doctor's (they don't have a doctorate and haven't done the residency and internship that a full-on doctor has), but they take on some of the lesser roles of doctors, handing some of the more routine and mundane tasks of a doctor. They have to report in to a full doctor as well.
The line blurs a lot more when you start comparing a PA and NP (nurse practitioner) - a nurse who has also completed additional training and licensure beyond the regular RN level.
If your cousin was a nurse, then she's still a nurse regardless of where she works, unless she somehow lost or surrendered her nursing license. Nurses can work in hospitals or in private practices, but they're still called nurses.
Edit: There are such things as '
freelance nurses'.
