Hi Please help me my 3 year old is suffering from severe cough and doc confirmed that he has allergy

Hi my son is going to be 3 years old this April.We have recently moved to mumbai in Septemeber 2010.and from then on his problem started. Mumbai is a very polluted place with vehicles and traffic.the place we are staying is on the 8 th floor.

He is continuously suffering from cough every week and when i take him to allopathy doctor.They put him on nebulisation ,allegra.Ascoril-LS,and Ascovent.
I am pretty sure that thases medicines in long run are not good for the child.

So did try homeopathy too.But did not work......:(
I did take him to a homeopath during one of the episodes and he had very high fever...of about 103.5 degrees....so had to come back to allopathy.

To give my sons details

1)He has a cough that generally aggravates during the night.It feels like he has phlegm in he chest but doesnt come out all the time.
2) he does sip little amount of water often
3) It generally starts when we take him out for a walk.
4) he has good sleep but i feel he dreams and talks about the days activities.
5)He is a little shy child and likes to be pampered always.
6)Likes to drink milk.
7) likes chocolates and ice creams.
8) his hands generaly are a little warm.

Can some one help me with medicines....I would like to give a try,,,,,,,,,,