Brief Answer:
Explained in detail

Detailed Answer:
Hello and welcome

Your concern is appreciated

Your complaints can be divided into two one is metallic taste and the other is that odour that you are having problem with.
Metallic taste in mouth can be caused by number of reasons like poor oral hygiene resulting in gingivitis periodontitis and other tooth infections
Prescription drugs like tetracycline lithium allopurinol can cause it medicine which causes dry mouth can also be the culprit like antidepressants
Multivitamins may be the reason for it and many other chemicals like lead or mercury
Infections like flu, sinusitis, allergic rhinitis or nasal polyps can change sens of taste
Dementia can also cause taste abnormalities
The odour you are having problem with can be actual ordour of something in your house if its reported by other people too but if its only you feeling it then it may be condition called phantosmia
Olfactory hallucintions
Smell is unique unpleasant spoiling taste of food or drink taken, there are wide range of causes like nasal infection ( sinusitis) nasal polyps migrain with aura
Dental problems certain chemicals and radiations neurologic causes include epilepsy Parkinson's disease ir Alzheimer's disease
Stroke head injury or brain tumor.

Investigation includes detail examination of oral cavity and nasal cavity nasal endoscopy MRI or ct scan

You can wash your nose with saline solution can try nasal drops and spray conatining steroids or anesthetic

You can discus all this with your doctor
please consultyour doctor before taking any further course of action

Wishing you best of health

hope it helps

Thanks

---