Lower Left Abdominal Pain (Chronic) ~ 1" inside hip bone

I have been having LLQ abdominal pain that is mostly constant for over a year now.  The epicenter of the pain eminates from approximately 1 inch in from my left hip bone.  I have been in for a pelvic exam and testing which showed no problems and a different Doctor I went to for this issue suggested a cat scan and colonoscopy, recommended against allergy testing, and was more concerned about a random bout of bigeminy whiched turned out inconclusive.

Because I have only major medical insurance, I want to make wise financial decisions about how to best come to some conclusions about the source of my pain and how to best fix it. (I have diligently set aside money in my HSA).

I am a healthy 40 year-old female who eats healthy and excercises.  I have tried eliminating certain foods from my diet (dairy, soy, & to a lesser extent wheat), but to no avail.  However, this condition seems to be worsened when I have a moment of weekness and indulge in pizza or a brownie (something unhealthy and processed).  

Both my grandmothers had diverticulitis, but my BM's seem to be pretty regular.  It seems I have a more frequent urge to urinate and have a BM though.

My husband, & I have not been using contraception for approximately 1 1/2 years and have not conceived (as far as I know).  

I do receive chiropractic from an old auto whiplash incident and have had hip pain after the birth of my daughter who is now 4 years old.

My questions are:  Do you have any suggestions as to what these symptoms might point to?  What are the most feasible medical steps I can take to come to some conclusions.  Should I be seeing a gastroenterologist or another field?  Is there any home testing, dietary changes, etc. I can do to help with the diagnosis?

Thank you so much for your help!