I have been on Tamoxifen (Treva)for 4 years now! This year I have noticed that I get terrible leg cramps at night and have started suffering joint pain. On Friday I developed an excruciating pain in my right thumb and I think I may have thumb arthritis. I am thinking the Tamoxifen has caused this. Yes I think I will go back onto glucosamine and cod liver oil to see if it makes a difference.