I am pleased to hear that you have got relief dropping back to 10mg/day. I have tried to research low dose Tamoxifen online but there have not been enough large scale clinical trials for the researches to be able to say that the lower dose protects enough. There probably won't be other trials either - there is no money in it for the pharmaceutical companies to fund trials for this drug unfortunately.
I might add that I was diagnosed with bilateral early stage breast cancer (both breasts) which is really unusual and twice as scary and of course I had to have twice the normal amount of radiation also. This is possibly due to me taking supplementary oestrogen for far too long (15 years+) as I had very severe menopausal symptoms and my GP kept assuring me that what I was doing was perfectly safe. There is no history of cancer of any kind in my family, but fortunately a routine mammogram picked it up as I had no symptoms. I am now angry with myself that I did not stop the oestrogen earlier, but I trusted my GP - possibly too much. I'll let you know what my specialist says at my next appointment. Yes, I know all about the hot doona in the middle of the night ....
All the best to you.