I am glad we have been able to shed some light on your symptoms.
Unfortunately, most doctors, especially the male ones, don't associate a whole raft of symptoms as being menopausal which can be really frustrating for the patients as you have found out!
Certainly joint pain and palpitations seem to be very common. As your hormones fluctuate so can your symptoms and this can be why you will get varying degrees of pain/discomfort. Unfortunately, the Mirena Coil will mask your own hormone levels (which will be falling naturally at this time), so it would be very difficult to do an accurate test.
Most women on the coil find at some time that their menopause symptoms 'break through' and sometimes that is all you can go with.
Joint pain is often caused by falling/fluctuating oestrogen and this affects the hydration of the joints, causing inflammation and pain.
You may find Devils Claw and Arnica Gel helpful. Check your diet too, as caffeine, high salt and sugar foods, and processed foods can all irritate the joints further.
I have just done a short video on joint health in the menopause and what you can do to help yourself so do take a look if you can. If you send me your home address I can send you some Arnica gel samples to try for the joint pain.
I would also suggest a magnesium supplement to help support your nervous system just now which is probably being affected by your symptoms and this is also great for mood, sleep and calming the heart!