Tamoxifen side effects?

I've been on Tamoxifen for 3 months and can't say I'm having a very nice time. Hot flushes, night sweats, foggy brain, moodiness, fatigue, the list goes on. I have never felt to shit in all my life. I was diagnosed with breast cancer 5 months ago, had a lumpectomy and 4 weeks of radiation then started on Tamoxifen. I had been on the pill for many years, so stopped taking that immediately. My GP told me that I can't have the pill, the mirena, the implanon, etc and may consider a copper plated IUD, but last week I saw my oncologist and he said the Mirena is fine. But reading previous comments, other people have said they had to have theirs removed? Can anyone provide some further input for me please.