Okay ladies - I’m so confused!

I had a Mirena from 2011 after my first son was born & had no PMS symptoms or bleeding (except occasional spotting) until having it removed in 2014 to get pregnant with #2. I was back in my OB’s office 38 days after removal with a positive pregnancy test, had a healthy birth in 2015, & have since had 2 more Mirena with the same result - No PMS, minimal spotting.

In September, I had the Mirena removed again to start trying for #3. I immediately started seeing a regular cycle with my period lasting 3 days in September, October & a November. This month, I started spotting on the 15th & had 3 days of regular bleeding (16th-19th), then 3 days of no spotting at all, then started spotting again on the 22nd. From the 22nd to the 28th I had lower back pain I haven’t experienced in years, cramps, bloating, fatigue, random pelvic pains. The bleeding became grainy on the 27th & 28th & seems to have stopped today.

Any insight into why I am 14 days into my cycle & just stopped bleeding/having hormonal symptoms? Does this have any known correlation with fertility concerns or other issues? Has anyone had a similar experience after Mirena removal?