I'm not a professional, so please don't take my advice as gospel, but I went through a period of time where I was very fearful over my health, to the point where I imagined that I might have all sorts of disorders & diseases, like those you mentioned. At the time, I was reading about signs & symptoms of various diseases, and I would pick out one or two symptoms of just about EVERY disease out there, and I would think, oh no, maybe that is what I have!