Welcome to HEALTHCARE MAGIC..
I have gone through your query and can understand your concerns..
As per your complain in case if there is sinus infection
along with earache that can be due to infection in ear secondary to sinusitis
and post nasal drip
you can get a flare up of infection in the flight due to difference in the atmospheric pressure and it can lead to increased pain in the ear as well as sinuses..
I would suggest you to start taking antibiotics like Levofloxacin
for infection along with anti-inflammatory painkiller like Ibuprofen
, decongestants like Pseudoephadrine and mucolytics like Ambroxol..
You should do steam inhalations and saline nasal irrigations..
As far as taking precaution and treatment to ear your air journey is that you can take the dosage of medication before you board your flight..
You should keep painkillers with you in flight as well as you can keep decongestant nasal sprays to be sprayed if you find congestion and pain..
Hope this information helps..
Thanks and regards..
Dr.Honey Nandwani Arora.