The problem about flying commercially is you can't turn back . . . well, not without a lot of interviews. You really need to know if you will be able to tolerate the pressure changes. I assume c 8,000ft cabin.
Even when in good condition, the tube is something of a one way valve. Your real problems may occur on the way down.
I can get salty water (sterilized and about the mixture of sea water.) into my tubes, and have found it helpful in the past, but it takes a lot of messing about over the bath with head upside down, nasal cavity full of the brew and GENTLE nose-holding and blowing. Then not very gentle sniffing.
When it works, the noises leave you in no doubt about the flow.