I was given a prescription for Meloxicam and have so far tried it only once. (I've been having joint pain/swelling and general allover pain/discomfort recently, and my rheumatologist prescribed it. I also started taking Plaquenil about 4 weeks ago, but that can take many weeks to take effect.)
I am wary of NSAIDs generally because they can mess up the stomach lining, and I believe that leaky gut has been an issue for me. But I was feeling so terrible a couple of days ago that I decided to try it.
My prescription was for 15 mg, but I took only half a dose the first day. I am very small, and I though 15 mg just seemed like a lot to start with. I'm not sure how much it helped with the joint pain and the overall pain. I still felt pretty uncomfortable, but assumed that maybe its effect was modest because I'd taken only half a dose.
I took the pill in the morning. In the evening, and continuing into the next morning, I had an unpleasant, sporadic feeling of chest pressure. (It was unpleasant enough that I called my doctor to ask about it.) It eventually subsided. I do not know if that was a side effect of the Meloxicam. It's also possible it was a side effect of the Plaquenil (which can take time to build up to therapeutic levels in your system, so I suppose it's also possible that side effects might also appear weeks after starting it.
I haven't taken it again since then. I don't know the answer to your question about the low ferritin. (I tend to have low ferritin as well.)
Started herbal treatment for Lyme in early 2017. Did 1 month of doxy Aug. 2017; started doxy again Jan. 2018. Uncertain about diagnosis b/c tests have been iffy, and my symptoms (dry eyes/mouth, finger joint pain/swelling) look like classic autoimmune issues. Different tests at different times have shown Lyme, babesia, bartonella, ehrlichia -- most recent tests show only Lyme (IgM bands only).