My son has got severe cough with fever.first foc gave tusq and colpol and inhaler for3days.but cough got increased then we took chest xray.doc told that he had chest infection.need to give antibiotic through iv for 5days along with tusq colpol and neubulisation. i couldnt able to understand how infection happend.why antibiotic is needed through iv.why so much of medication needed.