Does he have any cough with or without expectoration? If he has this localising symptom, and if what the doctor heard is suggestive of a lower respiratory tract
infection, go for an antibiotic, cefixime with levofloxacin
. If no localising symptoms or signs, it's better to wait for 2 days before starting an antibiotic. Have a blood culture
for enteric fever
and a complete blood count
. If he has burning micturition or a high colored urine, go for urine routine also.
What u say, the low back ache, knee pain, weakness o legs are ll constituitional symptoms of any infection. But, if the weakness of legs worsens, he needs immediate medical review