RA or Lyme arthritis?? are there telltale symptoms??

I am still awaiting diagnosis.  I have heard as many dx as doctors visited so far.. But these 2 (RA or Lyme arthritis) are most probable.

Can anyone of you who are more knowledgable about RA tell me if there are telltale symptom differences?

My arthritic symptoms are mostly in all large joints, but also 2 fingers, rarely. RF has been negative all the time. Can it still be RA or some other kind of autoimmune arthritis?

thank you very much for all advice. I am just too confused. Also, can RA develop because of Lyme disease? This is what one doctor in my country tells me, sounds strange though.

thanks

A.