Hello I am Dr Ravinder Sharma ENT surgeon
On the basis of information provided it appears that you have infection of one lung (may be bronchitis
, or pneumonic patch). It is difficult to make out the probable cause with this much information. There are quite a good number of conditions which may affect one lung. I would advise you for a ENT consultation and a Chest consultation to resolve the issue.
I hope this answers your concerns. Feel free to contact me if your need more information on this
With warm regards