I'm also on twice a day Ranitidine (Zantac) 150mg. I know what you mean by being aware of every little ache in your body and wondering what it could be. I had my GB removed a month ago and haven't fully recovered so my thoughts are constantly on every single thing that doesn't appear to be normal as I remember normal being. I'm not sure if it's the meds or my mind but I do understand what you mean about worrying.
Tony