How To Treat Loss Of Appetite Caused After Vomiting And Constipation?

Hi. My dad is reported to be vomiting, sweating, feeling very cold and having decreased appetite. Apparently he was constipated for about a week. Mom made lots of fruit salad for him then on Thursday he lost his appetite, started feeling nauseous, and saying he felt generally sick. He vomits even more after drinking water. Milk doesn t seem to cause any problems so that is what he is living on since Thursday. Could it be the constipation that disturbed everything?