I have been on it now for about 8 months.In the beginning,I also had that cramping,and then some light bleeding.I had to see a gynaecologist/onco and then I had a simple exploratory surgery.All was fine,and he explained it would settle down,and is not uncommon when you start Tamoxifen.It did settle,and the only side effect I have now are hot flushes/ prickly heat sensation.I had some nausea early on,but that stopped also.I think just give it some time,and try to do some daily exercise like walking,Cheers Robyn.xox