Hi Nas
I had a mirena in peri due to 'gore movie' bleeding issues. Had it fitted under GA (severe health anxiety) and so it took me a couple of days to get over those effects. I can remember it did feel weird, difficult to describe, and I think some of that was not knowing what to expect. I believe I've also mention ablation and cauterisation to you previously.
Anyway, my experience was that the immediate effects, including cramping, settled within a month. However, it took six months for the mirena to totally stop my periods (wasn't through meno, I had blood tests). At this point, I felt I had my life back, at least from the horror film bleeding and constant anaemia. I wasn't just surviving my body and instead could make plans and stay vertical.
One of my daughters has recently had a coil fitted (contraception) and she found cramping, bloating and a bit of bowel disturbance for six weeks or so. Seems to have settled now.
Re: other published side effects, yeah, health anxiety is great for ensuring we look all those up. I'm convinced my mirena did cause weight gain (I've had two over the years), but only a stone, and it's not super hard to keep on top of that (except I like kit kat too). To be honest, mentally, I couldn't really say. The maddest I've ever been was while I was on HRT, but there was a lot of other stuff going on at the same time.
Once blood tests showed I was through the menopause, I had the mirena removed. All good.
In conclusion, I'd say it was a lifesaver for me, because my bleeding was just so catastrophic. As soon as that was under control, I was able to focus on other health stuff. So I'd say push forward with paracetamol and rest and maybe allow yourself to feel confident that this is going to work and by September (teacher here also) it'll all be a completely different kettle of fish.
Best
EK