I agree with Renae - review the results with your doc. I have SLE, RA, Sjogren's, Raynauds and possibly Fibro - but I tested negative then positive then negative then positive for a couple of months before my bloodwork finally rested on positive.
Be persistent with your doctor, talk about your symptoms - it helps sometimes to write them down. Express that something isn't "right" with you - and you want to find out what is going on. Ask what else can be done. Sometimes it may mean jumping up and down some, but it's necessary to drive home the point that you're physically miserable.
Keep us posted and best of luck!