Make sure to read this thread:
http://www.pprune.org/medical-health...hian-tube.html
Make sure to get a tympanogram ASAP. Considering this affects you in a professional context, I would be inclined to obtain a full battery of tests at a specialist audiological / ENT facility.
Oh yeah - as you'll see in the link, there are drugs known as 'mucolytics' which thin one's mucous - could be helpful in your case.