Vomiting at night?

[ScruffyTeddy]

Hi,
My friend's daughter (age 10) for the last four/five days has been unwell. She's mostly fine in the day but starts vomiting at night. Have you any ideas on what it may be? Surely a bug wouldn't last this long?

My dd has been been unwell for nearly 2 weeks, and vomitted continually for a couple of days and then was vomitting at night for another 7 days. She was an underlying health problem anyway, so the jury is out as to whether its a bug (there is a sickness bug knocking out all her classmates) or her HSP. I thought I saw an earlier thread about a child vomiting at night but can't find it now so would be interested in others comments on this one too.