Also, for the temperature, did you use a thermometer?
Kindly use a digital thermometer to check. Any reading higher than 37.5 is a fever and you should see a pediatrician for follow-up as advised.

Was a malaria test done and malaria confirmed before the initial treatment?
And was it a doctor that prescribed those drugs you've listed?
Please, note that self-medication is not right.

If a doctor did see your son and prescribed the drugs, kindly go back to the hospital and explain you've not seen changes.