Hello There.
I can understand your concern.
ask him to drink lots of water and have a soft diet.
also, take a paracetamol 500mg thrice a day and monitor his temperature properly.
kindly get a
Complete blood count, Urine complete, Malarial parasite and Widal test done. and consult a general physician with the reports for further help.
best regards, Dr. Anil kumar jain.