I started taking fosamax 3 weeks ago. The evening after I take the pill, I experience severe joint pain in the knees and back. Once it felt like my shoulder blades were lit on fire. These symptoms only happen while I sleep and leave after I am up for 10 minutes or so. I am scared to keep taking it; but, my bone mass has dropped 10%. My doctors cannot tell me if the pain is good (it's working) or bad. I am so confused and worried.