Night fever for last 1 month & breathing problem

Yes, don't try to diagnose your child's condition by things you read on the internet.
If you are not happy with the diagnosis and/or treatment given by your Doctor, go and get a second opinion or ask to see a specialist.

Definitivelly you need a second opinion. I don´t thing these doctors are doing the correct work up. Does he has respiratory problems like difficulty breathing on exertion or a wheezing sound on his chest? becuse Salbutamol is used for bronquial spasm and nothing like that is on your resume.
Search for a new pediatrician so he can make a good work up. Ask with friends for someone they trust, i had always thought that is the single must important thing to search on a medical professional.
So my differential diagnosis according to the information you provide will be: chronical acutized sinusitis (special head x ray and clincal examination), adenoiditis (special head x ray and clincal examination), allergic rinitis (personal and familial clinical history, cultures, nasal secretion evaluation), pertussis infection (a quite persistent bug we call this desease the 100 day cough cause it trends to last up to 3 months even after appropiate treatment), rinopharingitis of an atypical bacteria (ruled out with a culture).
So i insist. Look for a second opinion soon.