Brief Answer:
ETD takes 2-3 weeks
Detailed Answer:
Hello sir,
 The steroids  mentioned previously are for local action and have no systemic side effects so can be used safely.
The 
betnesol tablet for gargles will decrease the inflammation faster and healing will be faster.
Regarding nasal steroids, they will act for both nasal disease and 
Eustachian Tube Dysfunction also.
Plain Steam inhalations will do.Other menthol drops etc will only give false feeling of opening the nose  but will not help in ETD
Do continue with 
Loratidine.
ETD lasts for 2-3 weeks.
If the current symptoms is troubling, you can take 
lorazepam briefly. Avoid taking it for long duration. 
I personally do not favour allergy testing .
You can start with steroid nasal sprays which will take care of all allergy and will help in open up the nose and treat ETD.
You can also take mucolytics like 
ambroxol  and do chew chewing gums , its looks senseless but it does help. You might understand some of the medicines I suggested above are not over the counter.
Most importantly ,i advice you to see your 
ENT specialist to get nasal 
endoscopy done and to evaluate the nasopharyngeal area for any mass etc, as any mass in this area can present with ETD which is refractory to medicines. If endoscopy is not available then do get done MRI scan especially for nasophayngeal area. 
 I can understand its a annoying problem but it will go away.
Regards