Hi welcome to HCM.... A lot of mucus in nose and throat can lead constant irritation and so nausea can be there .... Here you can have mostly sinusitis infective condition..... You should be investigated with Digital PNS x ray for sinuses to rule out sinusitis .... Steam inhalation with added eucalyptus oil two drops in hot water daily for three times a day .... For mucus excretion you can take ambroxol Cough syrup or tablet .. Take cefpodoxime proxetil tablet bd for five days .... One tsp ginger juice mixed with one tsp honey taken for congestion relief.. You can use decongestent like cetrizine or higher one benadryl .... Oxymetazoline nasal drop used three times a day for three days ... You will recover in week.... Advise : consult otorhinolaryngologist and discuss all this. .. Take care