Saying to someone that sneezes repeatedly, “May Allaah have mercy on you”, and supplicating for him

If I hear someone repeatedly sneeze, should I say each time Yarhamuka-llaah!, May Allaah’s Mercy be upon you!? Has the statement Shafaaka-llaah!, ‘May Allaah cure you!’ been reported?

There is an authentic narration that a person who sneezes and says, Alhamdu llilaah!, ‘Praise be to Allaah!,’ Yarhamuka-llaah! should be said. If he sneezes more than twice or three times, then he should be supplicated for and informed that may have the flu.