I have been on tamoxifen for four years, just starting my fifth and hopefully final year. I had slight nausea and dizziness in the first few weeks but that passed quickly. I had mild hot flushes which continued for a couple of years. But maybe I would have had them anyway as chemo put me into menopause. Still get the occasional one actually. Otherwise no real symptoms that I can definitely attribute to tamoxifen. Managed to avoid gaining any weight which was a big fear for me but I have to be vigilant with that and exercise regularly/watch my diet.
I do struggle to get a good night's sleep at times but then that's always been a bit of a problem for me so not sure if tamoxifen has made it worse. Will be interesting to see when I go off it next year. Incidentally I always take mine in the morning. Thought it would be less likely to interfere with my sleep but who knows really. I would suggest you hang in there with it. Hopefully the side effects will ease. I think all the usual healthy lifestyle tips help ie regular exercise, healthy diet, minimal alcohol and caffeine. Good luck. I hope you feel better soon.