Hi..
Welcome to HEALTHCARE MAGIC..
I have gone through your query and can understand your concerns..
As per your complain nasal 
drainage along with bad taste in mouth and smell can be due to infection in sinuses also known as 
Sinusitis..
I would suggest you to consult an Otolaryngologist and get evaluated and a thorough clinical evaluation and investigations like PNS View x ray or MRI Scan can help in diagnosis and treatment can be planned accordingly..
He can advise you a course of antibiotics like 
Augmentin, anti-inflammatory painkiller like 
Ibuprofen, decongestants like Pseudoephadrine, anti-allergics like Levocetrizine,steam inhalations with a few drops of eucalyptus oil in boiling water..
Use a humidifier in your room..
You can also do saline nasal irrigations, decongestant nasal sprays and 
steroid nasal sprays..
Avoid chilled foods and air conditioned atmosphere..
Do warm compresses around nose..
Hope this information helps..
Thanks and regards.
Dr.Honey Nandwani Arora.