Hi..
Welcome to HEALTHCARE MAGIC..
I have gone through your query and can understand your concern.
As per your complain rusty taste in back of throat can be due to mucous formation and there is a possibility that there is a superseded and recurring bacterial infection leading to infected sputum and can lead to a foul taste..
The other causes can be
acid reflux, side effects of medication, allergies and
post nasal drip..
You should consult an Otolaryngologist and get evaluated and diagnosis and treatment of the underlying cause can help in improving the taste,,
As of now you can drink plenty of water..
Do warm saline gargles and steam inhalations..
Chew sugar free flavored chewing gums to mask the bad taste..
Gargle with a flavored antiseptic mouthwash can help..
Hope this information helps..
Thanks and regards.
Dr.Honey Nandwani Arora..