Hi @JoHobbs, sorry to hear about your story. It's a whirlwind isn't it. I had similar treatment to you.
I started on tamoxifen in November 2020 and lasted on it for 20 months before having a 6 wk break and now I take Letrozole. We all react differently so it's hard to say what will happen for you.
When I first started tamoxifen I had alot of hot flushes but it settled down after a couple of months. I always woke up at night for an hr or 2 but I just went with it. After about 16 months things changed again and I started to get so fatigued and breathless, even going upstairs was a struggle. I never got joint pain with tamoxifen. I wasn't aware that was a possible side effect. It's more common with the AI meds.
I booked in to talk to my oncologist about my side effects and she immediately ceased tamoxifen. She suggested I have a break. Oh wow my life was just wonderful without it however my cancer grade was high and my risk of return high so I needed someone else.
Originally the oncologist thought I would go back on tamoxifen after a break but the breathlessness issue was too much of a concern and hence now on Letrozole. So far I am ok but really stiff and a few joint pains I am trying to manage.
I would suggest sticking with tamoxifen for now. See if it all settles down. It might. Talk to your oncologist. Have a review after the 6 wk mark. Are you doing any stretches for your joints or some yoga. I know you get tired but even 10 mins to start with may help. Some members have medicinal cannabis and find it helps.
Good luck with your treatment.