Mirena coil and bleeding - what's normal?

[Jenala]

Had mirena put in in August. It's been ok, a couple of weeks of bleeding initially then somewhat irregular but very light 'periods' since. A few weeks ago i noticed during sex was sometimes a bit painful and i get random abdominal pain too. However even worse is that today is now the 28th day I've been bleeding, up and down in terms of flow but the last week or so fairly heavy with horrible cramps. It's starting to really do my head in. I don't like tampons much though I use them sometimes but the constant sanitary towel use is getting quite uncomfortable now. Plus I want to have a full sex life
I had a coil check booked and she said it all felt fine, she took a swab just in case and a pregnancy test. I've got an appointment to have a scan to check internal placement but interested to hear if this sounds similar to other people's experiences?