My wife had the same type experience during her Open Water cert dives. Upon returning home she went to a local ear/nose/throat Doctor and was prescribed a nasal spray and Allegra D. She takes these religiously before any planned dive trips. You may also want to take a look at this excellent web site: Doc Kay's diving medicine
http://faculty.washington.edu/ekay
Best of luck!
harry
http://faculty.washington.edu/ekay
Best of luck!
harry