7 weeks late today negative on every test I've done!!!

I don't know what to do, I have very bad backache, stomach pains, sore hips, im emotional all the time my SO's mother thinks I'm pregnant so does my sister. Anyway I keep taking tests but they keep coming back negative all the time my gp is a waste of time as they won't do anything else to help me could it be something else which needs to be ruled out? What do you people think as I need advice!!!