Vomiting, loose motion, stomach pain.

My kid started vomiting two days back, continuosly non stop even after water intake. She also had mild fever which subsided after paracetamol syrup. We took her to the local pediatrician he suggested for an IV and vomikind,  antibiotics via iv. She was admitted in hospital.  After the first iv she was vigorosly shaking and her fever rose up suddenly above 102. They gave tablet analy and paracetamol syrup. After vomiting stopped and she was a little better we were discharged. Her food intake is just started and her poop also is solid. Fever also subsided eventually. She still feels vomiting sensation after drinking water or eating. She also complains about stomach pain. And her stomach feels hot. Please suggest what should I concern about now and how to continue with her treatment. How long will it last? She s already underweight.