Hey there & welcome. Great that you found HealingWell! Glad to have you.
So this is tricky! Once you show a positive RF it typically doesn't go away...it can increase or decrease but it is a titer (like chicken pox) and once it's there...it's there.
The doctor's are foolish if they are basing their diagnoses on RF alone. Many people do not have the RF show up in their blood...it is positive in the majority of RA patients but not 100% of the time.
A more specific look would be to have your knee synovial fluid analyzed.
The docs should be looking at:
Morning stiffness lasting at least 1 hour for at least 6 weeks.
Swelling of bilateral joints.
WBC, RF and ANA and ESR bloodwork.
Fatigue, weight loss, fevers, loss of joint mobility.
Radiological changes evident in joints.
So when do you see the doc again? It could be the labs fault with the bloodwork, it is possible for error. I would have it repeated. And keep a journal of your joints & how they act.
Do you take any NSAIDs or steroids? Do they provide relief?
So many of us get the runaround for months and years before proper diagnoses & treatment. Don't be afraid to speak up & voice your concerns especially if they are interfering with your life.
The very best to you. Write back soon.