Tamoxifen side effect question

I started tamoxifen a little over a week ago and so far I haven’t had much in the way of side effects (yay!). One thing I’ve noticed though is that when I’m still too much, areas where I’ve previously had overuse injuries are sore/tight. Almost entirely on the right side of my body which is normal for me due to scoliosis. Is this a thing or is it soreness from painting? I don’t see why my knee and shin would be sore from painting lol