Hi, thanks for your question.

You had rhinitis for one and half week. Now you’re having swollen and sore mouth, stuffy nose and severe cough. You think your symptoms are due to sinusitis.

Yes, you're right you may be having sinusitis.
Sinusitis (infection of sinuses) is a known complication of rhinitis.

Rhinitis has also produced pharyngitis, which is giving you symptoms of sore and swollen mouth. Sever cough is due to decongestant and cough expectorant.
Steam inhalation is also advisable that will help your stuffy nose.

Consultation from a physician is encouraged to look for any other complication of sinusitis.
Hope I answered your question.
For any more query, do post your follow up, I will be readily available to answer.
Get well soon
Regards

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