I saw your question posted on saturday April 2012 only now ( Indian standard time 21.45 hours, Friday june 29th).
Clearly this answer will not help you, but being in the public forum, may be helpful to others.
We will analyse one symptom at a time
1. Marked reduction in activity: This is very typical in all febrile illness. But the child should be remain alert once in 8 hours or if sleeping easily arousable. If awake should be interested in what is going on . This should be there for few minutes atleast. child should be able to respond your questions.
is not working.: This is the commonest worry of parents. Paracetamol response should be assesed in two ways. After giving paracetamol the childs temperature should come down, and secondly the childs activity should go up. No harm if this lasts only for one or two hours. Fever
will rise up again and the child become lethargic
3. Not eaten the whole day
This is acceptable, provided her fluid intake is sufficent : she should pass urine once in 6 to 8 hours
4. Regarding hospital visit:
Hands and feet are cold
and if they persist a hospital visit is a must. That means even after giving fluids, keeping her warm, limbs
are cold means consultation is needed.