You hit the nail on the head as far as I'm concerned, with your question about
a lip biopsy... how will the results affect treatment?? I personally am not a fan of the biopsy, and would rather do a trial treatment.
As to your questions -
1) Bloodwork is almost alway ambiguous with auto-immune diseases, they are diagnosed by a COMBINATION of blood work and symptoms. There is not a single blood test or symptom that says YES or NO, it is the combination that indicates a diagnosis. And sometimes the diagnosis is still iffy until they figure out how you respond to treatment.
2) Diagnosis with a lip biopsy, as far as I know, is related to people with dry mouth. Sjogren's doesn't necessarily affect the mouth, so I don't know why a Dr would push for the biopsy. You can search this forum for people recounting their biopsy experiences. Most rheumies would try plaquenil without a lip biopsy.
3) Plaquenil results usually show up in 2-3 months. I don't know about
it's safety with doxycycline. The possible eye problem with plaquenil are related to field of view, and shouldn't have anything to do with floaters. Ask your ophthalmologist to be sure, and to get a baseline test early in your plaquenil treatment.
We aren't Drs and can't diagnose Sjogren's or anything else. Plus you haven't really shared your symptoms - what is dry? While a Lyme Dr can certainly prescribe, I personally would want a rheumy to do it, as the Lyme Dr isn't the expert in Sjogren's so couldn't adequately track your response.
Hope that helps.
Lynnwood, Lupus & Sjogren's Moderator, Dx: 2002DIAGNOSING LUPUS & HW's LUPUS 101
"Life is far too important to be taken seriously." - Oscar Wilde