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You seem to have a typical case of laryngitis associated with viral infection. You should rest the voice, that is, speak less until you feel like the symptoms are resolving.
Avoid throat clearing as it irritates the throat further and hinders healing.
Steam inhalation three times a day will help with both nasal/ sinus congestion and post nasal drip.
You can add small amounts of menthol crystal to the steam which works better than steam alone, but do not add too many.
You can use intranasal steroid spray called Budesonide one puff in each nostril once daily for two weeks. Consult your specialist doctor, discuss with him or her and start taking the medicines with their consent.
Since you already have dry nasal mucosa, do not take antihistamines.
The cough is brownish because it may be mixed with little blood which may have come from irritated throat lining. Too much throat clearing or coughing can lead to minor tears in the throat which heal rapidly, so do not worry. However, if there is fresh blood, you must see your ER doctor.
Acute laryngitis, which is very likely what you are suffering from, resolves on its own in a week. If symptoms worsen or do not improve in a week, or if you come down with fever, you may require oral antibiotics.
Hope this helps.
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