How can I cope with fear of ALS?

I am a 22 year old male, and lately I have been consumed by what I believe is an irrational fear, but I cannot seem to shake it. It started when I realized my arms and legs have minor twitches fairly often. These twitches are usually unnoticeable but persistent none the less. I went online out of curiosity and suddenly uncovered ALS. Now I'm terrified. I think about it every day, no matter how much effort I put into ignoring it. I constantly test myself by working out, deliberately trying not to be clumsy, running up and down stairs, etc. I even started looking up isted suicide for ALS sufferers. I am so frightened of being paralyzed and trapped in my own body that I cannot live a normal life. I read the horror stories of the people who are afflicted at a young age and it breaks my heart as well as petrifies me. It seems that no matter what I'm doing, the forefront of my thoughts are on ALS. If my arms start to shake while doing push ups, I think of ALS, if my legs start to tremor while I stretch, I think of ALS. Tickles in my thigh, chest or arms: ALS. I just want so badly to focus on my schooling and career. I want to walk the streets and listen to music and be in love and do all the things that embody youth, but my fears bury me in what feels like an inescapable hole. Has anyone else experienced this? I don't have the money to visit a doctor for expensive testing, not to mention, the degenerative nature of ALS is difficult to test without the page of time. I'm normally very calm and logical about most problems, but this one seems to have consumed me from out of nowhere. I also have terrible sleeping patterns and wake up throughout the night, as well as a shaky diet. I eat healthy but I don't eat a lot and I may be lacking in vitamin intake. I am also under a lot of stress and pressure. I have heard that these may factor into the twitches.