Paul
Found youre bit about youre "Clacker" problem rang true with my experience. A couple of years ago whilst working as Divemaster in Turkey after the final days dive I had an identical experience. It basically felt like I had something stuck in my throat as the dam thing had swelled up. Initially have to admit I got the wind up as the thought crossed my mind it may have been decompression related, despite no stops missed and well with NDL's.
The swelling went down after a few hours although I was still conscious of it not being 100%.
On returning to the UK It didn't get any better,and caused some coughing eventually after seeing my GP who was perplexed with my symptoms, I got refered to a Consultant. The consultant still mystified by the cause could only offer Surgery. In short I had the dam thing removed by lazer off. A bit drastic I know but solved the problem.
Dry air?
???