Sounds as if you're doing a good job, and have wisely consulted advice.
Maintain fluids. Small volumes, frequently, e.g. 20+ mLs every 10 minutes. Electrolyte solutions, such as Hydralyte or Gastrolyte are good. If he is not able to tolerate liquids, Hydralyte icy-poles are often tolerated better. Ice chips are often tolerated better than water.
Fever can be controlled with either paracetamol or ibuprofen in liquid form. Both can be used together for fever within returning in less than 6 hours. Giving alternating medicines every 3 hours. Maximum of each medicine: 4 times a day. Remembering that repeated doses of ibuprofen should not be used without food, because of the risk of stomach injury from the ibuprofen.
If he looks unwell he should be reviewed by a competent health professional.
As you have said food should be offered when hungry. Allowing for my earlier comment on ibuprofen.
As stated reduced urine output is an early sign of dehydration in children without chronic illness, e.g. diabetes. Later signs are dry mouth, dry eyes, no tears when crying, lethargy and reduced level of consciousness.
If your concerned and do not have speedy access to a GP, go to your local Emergency Department for assessment and treatment.
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