I too have had terrible dizziness. That is one of my worst symptoms. I still have it and I'm two months post removal, but I feel like it may have been a little better the last several days. I have been told by doctors that there is fluid on my ears, but nothing they give me gets rid of it. I too have thyroid problems so I'm not really sure what the cause is, thyroid or Mirena. Either way, I'm hoping that it gets fixed soon. I'm going on 6 months of dizziness and it is really starting to wear me down.
I started menstrating about 2 days after removal and bled quite heavily for probably about 5 days or so. Then I had another period two weeks after that and another 4 weeks after that, so I seem to be getting more regular. I think I recall reading many people that bled heavily within a few days of removal.
Sorry you are going through this. It really is the pits. I hope you have a speedy recovery.