Hi Aquaholic. I'm so very sorry to hear of your food intolerances. That's an awful way to live. I eat gluten free and that's hard enough.
As for the lab tests, it wasn't too many years ago that platelet volume wasn't (couldn't) be measured. As a medical technologist (BS in lab) I place platelet volume in the "thanks for the info" category. Now platelet count is very important, especially if it's low. A low WBC is often caused by viruses and can change within a day or even hours. Your rheumy might also be right about the cause.
If you had a series of antibody tests run, such as anti-double stranded DNA and everything was negative, probably all you can do is wait for them to become positive. At least that's what I had to do.
I sure hope you can find some relief for all your problems. Love, Butterflake