Hi..
Welcome to HEALTHCARE MAGIC..
I have gone through your query and can understand your concern...
As per your complain and presentation of symptoms it seems that you are suffering from
SINUSITIS that is infection and inflammation in the sinus lining leading to bad smell from nose and mouth as it is the most common cause of Sinusitis.
You should consult an Otolaryngologist and get evaluated and after a proper clinical evaluation and x-rays like PNS view and
CT SCAN as per the requirement has to be done to rule out the exact cause of the bad smell and treatment can be planned accordingly..
Without a proper diagnosis taking antibiotics can be harmful and frequent intake of antibiotics can lead to
drug resistance and certain antibiotics will not further fight infections in your body..
So it is better to get treated properly..
As of now you can do steam inhalations and use saline nasal sprays.
Hope this information helps..
Thanks and regards..
Dr.Honey Nandwani Arora.