Hi , welcome to health care magic, I am sorry that you feel unwell
Symptoms such as postnasal drip (drainage
down throat), cough, warm flashes/fever, nausea ,congestion in throat are consistent with a upper respiratory tract
infection (sinuses, phraynx, larynx and nasal passages)which are usually viral.Bacterial infections are suspected if it last longer than expected (beyond 10 days to 2 weeks), and very high fever
The infection is usually futher defined according to the part of the respiratory tract involved, in your case rhinitis
Treatment would involve rest, the use of copious fluids. In addtion you can try using medications such as : mucolytic
(decreasing the thickness of the mucous may help), intranasal corticosteroid spray which would also help the postnasal drip, a decongestant will help with the congested sensation (you may be able to find a medication that combines mucolytic with decongestant).
You can use paracetamol
for the fever, avoid wearing clothes that will keep you too warm, drink cool liquids and you can also try fan therapy if the fever remains unresponsive.
If you continue to feel unwell despite these measures then you need to consider visiting your doctor in case it is a bacterial infection that requires antibiotics.
I hope this helps and I hope that you feel better soon