UTI will take around 5 -7 days to improve and pain in stomach may well be because of this or may be stress or drug induced gastritis
for this you can give antacid
sos and try to give paracetamol
after some snacks or meals.
fever should respond in another 2 to 3 days as the UTI subsides.
regarding cough please get consultation of your pediatrician
to assess the chest for any signs of congestion or chest infection
and if it requires treatment, may be the pain in stomach and fever is because of this chest infection. the cough more during night points to some congestion in the chest, and it has to be assessed physically only for any treatment.
wish rapid recovery to your child