If you have been on Mirena without success and have been using this method with success for year and now is the first time you are bleeding through, it seems like a real medical issue. Perimenopause might be at play. Better see a gynecologist!

When something is out of pattern, it is alarming.

I used to faint easily, but nothing bad happened. when I did not have insurance, I once fainted at the top of a carpeted stairs and fell down. I could not afford going to see a dr and I figured that since I had been fainting on occasion since age 16, fainting at age 30 would not do much harm. I was right - when I eventually got a job+insurance and saw a dr., he confirmed that I had an innocuous condition that can lead to occasional fainting which is harmless.

Your case is the opposite - everything was well up until now, so this IS an alarming situation and you better get checked out.

I hope everything checks out well.