Lower Chest/Upper Abdomen Aching/Discomfort

[VideoGeek]

I'm hoping to get some help with what I should do next.  I'm a 33 year old male, former intermittent smoker with symptoms that started in May of 2007, consisting of slight shortness of breath, a strange ache in my neck/throat, frequent throat clearing and sputum production (occasionally with brown flecks or bits of food), and chest tightness and aching.  I've been to a couple of doctors, an allergist, and a pulmonary specialist - I've had a couple of chest x rays, a CT scan of my lungs, pulmonary function and spirometry tests, a stress test and heart ultrasound, and a nuke scan of my chest for blood clots.  All have come back normal.  Currently the discomfort and aching seems to be centered around the lower left side of my chest and across to just below the sternum in the area of my diaphragm.  I don't have any acute pain, but more of a persistent dull aching there that sometimes I feel in my back as well.  It's very uncomfortable when I put pressure below my breastbone.  Also, I frequently notice a twitching on the left side under my lowest ribs when I lie down at night.  Initially, because of the chest symptoms, I was concerned about allergies, mold sickness of some sort, or even blastomycosis (because of the non-acute nature of the symptoms and the fact that I concurrently had chronic epididymitis), but now I'm wondering if I've been barking up the wrong tree.  I plan on returning to my primary care MD in a couple of weeks, and I'd like to know in advance what we might want to consider looking for.

Thanks for your help.