I don't know the natural way of saying "someone is visiting me and he/she is on vacation right now".
There's some ambiguity in "this person is visiting me" because it can be interpreted as the person is not here yet and is going to visit me soon. What I want to express is that this person is visiting me and he/she is here with me already. So does the following sentence make sense?
my girlfriend is visiting me from Canada and she just came last week