Ankylosing Spondylitis Or Fibromyalgia?

I'm 30 years old and have suffered back pain and knee pain to an almost debilitating stage and the fatigue can be immense. I've had this since I was 17 ish. Quite often out of nowhere my knees will 'pop' or 'crack'. This can be when I'm walking, starting to sit, try to kneel or even stand still! Sometimes the pain is horrendous. I've also noticed my back has become less flexible over time (in fact my whole body). My calves feel heavy and my feet hurt like crazy. I find it hard to sit for very long without my spine hurting. My wife has tried massaging my back, but she hates it because she sees the pain I'm in. I have been to a Chiropractor, but I seemed only to get worse! I have been to the Dr and they seem to only want to look at one thing at a time rather than collectively. However, I do get some violent jolts or shakes which has been diagnosed as Myoclonus. It has been suggested by one Dr that I may have Fibromyalgia, however, I read through the literature and although some of it sounds familiar I'm not so convinced. By chance I then read an article in my local newspaper drumming up awareness of AS. I'd never heard of this before so I googled it and I would say the symptoms described struck a chord with me. I'm yet to discuss this with my Dr. Has anyone else found the same awkwardness in regards to getting to the bottom of what their suffering from? I'm convinced my mother also had it, although it was never confirmed. I can remember how much of a struggle daily life was for her. One Dr even tried telling her she was a bored housewife and that she needed to get out of the house more! Unbelievable. Anyway thanks for reading this, just trying to build up more of a picture of what it is I have :'