I have been on levothyroxine 75 for two months so far. I started ...

I have been on levothyroxine 75 for two months so far. I started off at 25 then up to 50 and now currently on 75. I have horrible lower back pain along with my knees aching too. It's all the time and Advil or aleve do nothing to relieve the pain. I am miserable and hate living like this. Doing some reading here and other sites I've read that this can be due to the med and some thing about the fillers in it. When I first started the the 75 that my doctor game me from samples at his office that were the name brand all was good. Now that I have been on the generic from my pharmacy I'm in pain. Am I off base here and does any one have similar issue's? I'm calling my endo when the office opens today to see him. Thanks for any info.