George - my mate Fabio had this problem and even lasted a bit after surgery.... now he practices jala neti (yoga - nose cleaning - google it) and a bit of pranayama y
yoga... this works for him - it may not for you but at any rate it is generally considered to be beneficial (but I am no expert so perhaps read around on this).
He got into this situation (he thinks) by doing alot of relatively deep spearfishing (25m to 35m) in Sardinia (... but doesn't regret it as the grouper tasted good he says
). So perhaps it is sinus trauma caused by deep diving ? I think you said that most of your dives are around 18m to 25m here in Guernsey but some down to 45m ?
His condition may be different from yours etc so I guess the first stop is the doc...
Good luck with it mate.
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Ed
