For diarrhoea & vomiting increase your fluid intake and consider glucose/salt preparations from the pharmacist, particularly for the very young. Dioralyte is a leading brand, but others are equally good. Also consider sugary drinks like diluted Apple Juice, Blackcurrant Cordial (not the sugar free one) or flat Coke depending on what the patient likes most. Loperamide (i.e. Imodium) can be helpful in adults and a 2mg Tablet can be  taken after each episode of acute diarrhoea, but can often cause rebound constipation in overuse.  Fever is one of the body’s natural ways of fighting infection. For comfort, you may wish to remove clothing and bedding, consider Paracetamol as directed on the bottle / pack