Welcome to Healingwell.
First off Lyme disease is a clinical diagnosis. This means a doctor should look at your history, symptoms, and blood work to make a DX
History....exposure to ticks....yes
symptoms....rashes, joint pain, fatigue, weakness....yes
Blood testing for Lyme disease and other TBI (tick borne infections) is very inaccurate. Between 30% to 50% of people with TBI will show negative with early blood tests, and go undiagnosed or wrongly diagnosed with other conditions such as RA, MS, fibro, IBS, and many other conditions. A bull's eye rash, or "circular rash" is a sure sign of Lyme disease.
Would it be possible to have RA, and Lyme.....sure
But I would have to ask, did you have joint pain prior to your tick exposure?? With Lyme disease you really have to be your own advocate. What is your heart telling you?