What test did you have for Sjogren's that was negative? I have primary Sjogren's syndrome and was diagnosed with the lip biopsy. It is the gold standard for the diagnosis of Sjogren's. It was done by an ENT and it healed well with no complications.
Do you have joint pain along with the dry eye?
In some cases, I have heard that a doctor can diagnose Sjogren's syndrome by the symptoms of the patient.