There is also swelling or pain in the facet joints, which is generally more than 2-3 before it can be diagnosed.
As for rheumatoid factor positive, it can be used as a reference, but it is not the main index;
Your back pain seems to be related to catheter examination. This symptom can appear a few days after the general examination. After all, it's an invasive examination, but it won't last that long. You have to find other reasons, such as scapulohumeral periarthritis, cervical spondylosis and chronic muscle strain.
I hope my answer is helpful to you.