Sorry about that...I can relate to being admitted in a Nigerian hospital, really stressful. We see a lot of cases of vomiting in kids without fever or diarrhoea, we term it gastritis, irritation of the stomach wall from infection or inflammation. It could be from the child's diet,infections like malaria commonly, food poisoning, positioning after breastfeeding could cause the child to regurgitate feeds
However it's a common presentation in kids following food poisoning and it's nothing to worry about, supportive antibiotics would help eradicate the organism, fluids. I just hope he wasn't given anti emetics last time to suppress the vomiting because it can be counter productive