Missed period

Hi everyone. I have the nexplanon implant, and I have since 2016. I’ve bled basically nonstop since getting it. I would have my period probably 20 days out of the month intermittently, always light. There was one time I didn’t get it for 2-3 months, which was only because I was given the Nuva ring to try to regulate it. Then it started back, and it was basically one week on, one week off. I now have not had my period in over two months. I took a few pregnancy tests a couple weeks ago, all of which were negative. I’m planning to go get my implant replaced soon and I’ll bring it up then, but I’ll likely go to planned parenthood and right now my local one is only open 1 day a week due to COVID so I have no clue when I’ll be able to get it done/talk to someone. I’ve also been experiencing immense lower back pain, which may be completely irrelevant (I’ve always experienced back pain) but not sure if that would be a factor in anything.

Does anyone have any input?