Thank you for asking your query at DoctorSpring.
Since the consult seems of urgent in nature I am replying as first response.
Your sister seems to be suffering from a Foodborne illness, probably from contaminated burger. Known as food poisoning this is an acute gastroenteritis caused by the bacteria or toxins in the food. (In this case probably the burger patty).
Most people with food poisoning get better without the need for treatment. But in your sisters case she has an alarm symptom which is reddish vomitus. This could be due to mixing of blood from the minor abrasions in the oesophagus or stomach. So I recommend an ER visit or urgent Doctor Consultation. She might need medications to stop vomiting. Also she might need an Intravenous Drip (to supplement the lost fluid).
To help relieve the symptoms she should rest and drink plenty of oral fluids. It is best to avoid food until you feel much better. When you start eating again, choose foods that are bland and can be easily digested. Drinking water (or ORS solution if available) is important. Usually no medications are needed.
This illness usually resolves by itself and if adequate care is taken no complications will occur.
Hope this helps
Please feel free to ask followup queries.