Never had an IUD, nor do I take Antibiotics . The "crackling" in your ears are parasites feeding off any metal filings, crowns. In 2009 I started hearing slight movement in my ears, and ignored it. Once I started my parasite cleanse I knew the noises were unwelcome parasites. I've used a myriad of essential oils in my ears, all results in sea monkey's dropping from my ears. Take a clove of garlic and cut it length wise, this shuts them up. If you don't believe me try it. I know it's gross, having garlic in your ears but no one even notices. I will sleep with garlic in my ears, and it stops the noises. Finally I have quiet in my ears.