Hi, sorry you are going through this. Yes, RA can be elevated when you have something else or, you could have RA, just not a lot of antibodies. My RA factor is about the same level as yours. The only way they could find inflammation in my joints was a bone and joint scan. No damage showed up on xrays and nothing showed up on a regular MRI.
You mention joint pain for 3 weeks but state you think you have Lyme and that it may go back 10 years. While Lyme is a definite possibility, have you had joint pain off and on all this time? Have you seen an infectious disease doctor or a rheumatologist?
Did they test your CCP? CCP is much more specific for RA and if both RA Factor and CCP are positive there is a 99% chance it is RA.
I'm in a very similar boat and am trying to decide whether or not to start meds. My joint pain is mild and has been going on for about 5 months. All other blood work except RA factor is normal.
Please keep us posted on your status.