IUD and period

(Sorry in advance for how long this is)

I'm curious if anyone else has had this issue. I have had my Mirena IUD for three years now. In about August of last year, I started getting cramps and spotting. Since then, I've had a pretty regular "period". It's not a normal period because I barely bleed, but I get all the other symptoms of a period and they last for 7+ days (my last one was two weeks long). I was previously on Depo, so I haven't really had my period for eight years.

I chose both contraceptives because they essentially eliminate your periods. I stopped Depo because of all the long-term side effects (mostly family history on both sides of osteoporosis). I'm fairly certain I've got endometriosis, so my periods are intense and painful.

I'm wondering if anyone else has gotten their period or something similar to a period after having an IUD for an extended period of time. My thoughts are that the IUD just isn't as effective as time goes on, but if that's the case, it's kind of bullshit to have to suffer for 2.5 years when they "last" for 5 years. If you are going through this, any recommendations for how to deal with these symptoms? I've gone to a gyno and she basically told me to "lay on my stomach to relieve some of the cramp pain", so any actual help would be great.