3.8 Month Child, Vomiting, Green Color Motion, Fever, Over Hungry. Taking Medication. What Kind Of Food Should Be Given?

My son is 3 year 8 months old. he was suffering from vomiting and ill health. on checking we found he is also suffering from less Hemoglobin i.e 8.8 as on 2/8/13. I have consulted doctor. she has given a tonic to give to him 5ml at night and one more for vomiting . He has started suffering from green colour loose motion since last week. doctor told me it is because of infection and she gave ZONOFLOX 5ml thrice a day. for the first day he had fever. now no fever but loose motion not yet stopped. and he is over hungry now. he asks me to give that and this frequently. after three days the stool has become light yellow color. but now again it has become green. I am so much worried what to do? how do i control his food habits. what should be given and what not????