If your health insurance has a website, search under "pediatric rheumatologist" to find one in your general area. Or call their 800 number. Even if you have to drive quite a distance to get to one, your son is worth it! If you need a referral, give your pediatrician the name of the the doctor you found and hound him until he gives you one! I so hope you will find a doctor you can trust and that will take you seriously. I know it can seem like a full time job! My ten year old daughter was diagnosed recently. I feel as if I have aged alot over the past two months! It's stressful.
Best of luck to you getting to the bottom of your son's problems.