Child Nausea and vomit in midnight.

Hi, my daughter is 2 years old, she is not taking any food except mother's milk from last 5-6 days. From last three days she is having nausea and vomit in her sleep and only in midnight and after vomit she sleeps well. She were fine in day time and there was no any other symptoms like fever, cry etc. yesterday my doctor suggested to have Syp ondem 5 ml twice a day & Syp ranidom PD 2 ml twice a day For five days. We gave this to her last night and today morning and after this she took half chapati today in lunch but after that she developed loose motion 4 times til now still no other symptoms and fever. We also gave her iron syrup to her in the morning. What could be reason of night nausea and vomit? What should we give her for loose motion and this nausea? Should we continue the dose I mentioned above? Thanks in advance.