How do you r/o lupus (sle & discoid), fibromylagia, polymyositis, and sjogren's syndrome from each other? what other tests can we do?

Too complicated.: These diseases are difficult to distinguish at times and often require observation and repeated testing over time. The biggest clue is the clinical symptoms and lab testing provides confirmatory support. If you do not have significant symptoms, there may not be any more testing you need to do at this time.

Very different: These are very distinct diseases that are best diagnosed by a rheumatologist with a thorough history and physical. Blood tests alone do not make the diagnoses.