What is the constant dull pain in lower left hand quadrant of my abdomen?

[choclatelab_1]

I am a 46 year old caucasian male, height is 6' and weight about 225.  For nearly two weeks now I've been experiencing a faint or dull sensation in the lower left quadrant of my abdomen along with like a pulsating or flaring feeling.  The pain (2 or 3 on 10 pain scale) is nearly gone when I am up and about, but seems to escalate slightly when laying down.  After about five hours of sleep at nigh, I do awake as I feel gas pain.   Two consecutive nights prior to all of this arising, I foolishly (probably) ate popcorn as a snack late at night prior to going to bed.  I am wondering if this has something with a kernel not being fully digested causing some irritation.  Anyhow, during this two week span, I've visited my primary care giver twice.  I have had no loss of appetite, no fever, no nausea.  There has been slight weight loss (5 or 6 pounds) because I was told to let my bowel rest by eating lightly.  So, the weight loss is solely due to change in diet.  I have continued to be fairly active exercising.  I have not been lethargic.  The first time I visited my primary care physician over this two week span, she probed where I mentioned the pain was.  She said it felt a little tender, and she could tell some gas was "stuck" (????) there.  Urine and blood lab tests were conducted, both came up normal, no sign of any infection.  About 4 days after the initial visit I went back to my primary care physician again since it seemed the pain just continued.  I was told a person can sometimes have a very nominal infection, which might not show up on the lab tests.  As such, I was put on a 10 day antibiotic, Levaquin.  The pulsating or flaring sensation mentioned earlier has stopped.  The pain "seems" to have subsided, I think, but has not gone away entirely.  Any comments, ideas, recommendations would be appreciated.