Thanks for writing in.
This IUD has no proven side effect of increasing the chance of bacterial overgrowth in vagina.
Although as you have a history of discomfort & infection that dates back to Mirena
insertion & you are not sexually active, then one possibility could be an allergy
to some of the component of the device.
I think it would be wise for you to get it removed. Please consult your Gynecologist for this & to get an alternative treatment.
Also, send the device for lab test after removal & get your blood sugar tested as well.