Assalam Alaikum .
If when you get up to keep the fast, but about 4 hours after you vomit can you continue the fast?
Wa Alaikum Assalaam,
الجواب و بالله التوفيق
In this case, you can continue to fast.
And Allah Knows Best.
Mufti Waseem Khan.
This answer was collected from DarulUloomTT.net, which is operated under the supervision of Mufti Waseem Khan from Darul Uloom Trinidad and Tobago.