Hello @Newbie3312,
I was on Tamoxifen for five months then had to switch to Zoladex plus Letrozole two months ago. The initial sudden drop or disruption of hormones on any of these drugs is tough. I had severe joint pains, bad insomnia and mood swings in the first weeks on Tamoxifen. It gradually settled down. The switch to Zoladex was fairly uneventful, probably because I had already been on the Tamoxifen. I have noticed joint soreness on Zoladex,/letrozole, but keeping active helps to keep it at bay. I hope you feel better soon. :)