Good day my 2 year old toddler has been coughing and now she started to vomit when coughing, is it something i should be consent about or it's just flue?

Not particularly : The muscles involved in coughing & vomiting are similar & young children often have difficulty not vomiting if they cough hard enough. I would concentrate of maintaining her fluid balance & see if she gradually improves. These are often simple viruses but need to be monitored closely.

Coughing associated with vomiting is often associated with distress; pertussis or influenza. An allergic reaction and bronchoconstriction is another possible cause. At this age, if there is post nasal drip, this may lead to irritation of the stomach lining and vomiting. Keep nasal passages clear with nasal saline drops, monitor your child's temperature, and follow up with your Pediatrician.