Hi,
A virus is the most likely cause, as you stated, though bacterial infections can sometimes occur. Treatment would normally involve:
(1) Holding off all solid food till there is a 4 hour window with no symptoms. When 4 hours pass with no
diarrhea or
vomiting, then you can start with small amounts of dry food such as the crackers or toast.
(2) Use liquids such as the gatorade you mentioned but use only small amounts at a time. This means using 1 tsp to 1 tbs every 5 mins for the first hour, if you tolerate this then increase the amount. If you vomit in between then the hour restarts.
(3) Probiotics - either on their own or with certain yogurts.
(4) Medication such as Peptobismol or
Dramamine would help the vomiting.
Pepto bismol may also help the diarrhea as well.
(5)
Paracetamol would help with the pain. The vomiting would contribute to the distended veins due to increased pressure. Vomit can come up through the nose since the passages are connected. It would inflame the pathway which would cause bleeding.
I hope this helps. Let me know if I can assist you further.
Regards,
Dr. Michelle Gibson James