I get this too, classic Tamoxifen symptom. It’s the estrogen being taking out of your body. I do find magnesium at night before I go to bed helps. Bioceuticals is the best one. Ironically exercise helps too with the stiffness I try to do 10,000 steps on my iPhone health app each day.
and every week I go and have acupuncture and remedial massage on my legs and ankles to clear out all the toxins that have accumulated. My health fund covers this and I just pay a gap payment of $35. I highly recommend doing something like this it really helps me. Good luck 😊