Sorry so late - I just saw this. It does appear that RA is linked to lung scarring: https://www.mayoclinic.org/diseases-conditions/rheumatoid-arthritis/expert-answers/rheumatoid-arthritis/faq-20058245
There's no one "tablet" that people with RA would be taking, so you should definitely discuss this with her doctor.
Pulmonary manifestation of rheumatoid arthritis include various forms of interstitial lung disease/fibrosis, bronchiectasis, necrobiotic sometimes cavitating nodules, and/or pleural effusion/thickening.
Check the medications, as some of them also can cause damage to the lungs (f.ex metotrexate), so always read the things, ask a pharmacist and discuss it with the doctor.
Very good she had symptom relief when taking D-vits! :) If taking NSAIDs, get the iron levels checked regulary, as it can inhibit the uptake of iron.