Stomach, Ulcers, Gastric Bypass Forum - Random Dry-heaving Occuring Everyday For No Apparent Reason?

Sorry for the longevity of this message, and I hope I am posting in the correct forums (i could not find another forum that seemed appropriate to this issue)

here's my story:

about 2.5 months ago I began a new job that entails a lot of new knowledge and a lot of physical training. Prior to obtaining this new job I never had any issues with any physical ailments or medical issues in my past. I've been healthy as anything since I can remember. As I began this new job (and subsequent physical training), I noticed that I would randomly begin to dry-heave at various points throughout the day for about 2-3 seconds and then it would disappear. It's come on rather suddenly and oddly enough it seems to be the only symptom of any ailment I may have. But I truly have no idea what could be causing this random dry-heaving. Here are some facts about it with me:

-occurs nearly everyday at random points in the day. Sometimes I am doing nothing but sitting and reading, other times I will be outside washing the car. And other times in between of course.

-occurs during my workouts everytime I do physical training. Usually running and aerobic-type workouts. (as of now I run about 3-4 miles a day and do alot of calesthetics(sp) nearly everyday as well. Have been doing this for about 2.5 months)

-occurs often when I venture into the cold. If I run outside to grab the paper or just go outside for a moment in 50 degree weather or below, I often times get this feeling of dry-heaving and I usually do.

-i have not yet actually vomited, only dry-heaved. And it usually occurs for about 2 secs then goes away for a while. If I breathe in real deep I can usually get it to go away without much fuss.

It began right as I began my new job and new training. I've been told it could be stress related, but i'm past the nervousness of a new job, and i've had a work and pt routine down now for a good 2.5 months. I rarely am stressed anytime before, during, or after work. This feeling hits me almost everyday (at random points in the day), and always during physical training.

My health besides this seems perfect. No other pains or problems, I sleep fine, I eat relatively healthy, no digestive problems really, very little junk food and soda, I dont take any drugs or medications, I drink a beer once a month maybe, and i'm in great shape overall, nor do I or have I ever smoked. I just have no idea where this dry-heaving is coming from but it's getting very discomforting.

My doctor did some blood tests and said everything looks fine except something to do with the liver or kidney (sorry for my lack of knowledge here, I know those are two very important organs, you'd think I could remember which one he was talking about) but i'm not sure which. He recommend I get an ultra-sound done and I plan on doing it this week.

Does anyone else have any experience with this, or any recommendations? Maybe some ideas as to what could be causing it? As I said before I have no other noticeable symptoms of any other disease or health issue that I am aware of. Any help would be great!