From what I have read, you are being extremely irrational. You are demonstrating classical cases of confirmation bias. You are actively seeking information that conforms to your belief while dismissing information to the contrary. How many times in the past, before you suffered from this anxiety, have you seen adverts about other diseases (any disease) and immediately thought it was "God" telling you that you have it?
I am guessing not many. You have probably seen tons of different adverts about various cancers and diseases but never thought much of it. And as a result of this, you may not even be able to recall many times where you have seen such adverts and dismissed them.
That's what confirmation bias does; regardless of how consciously aware you are of it, your brain will seek out information that it wants while dismissing information that it doesn't want. If you are constantly worrying about anything, whether it be ALS, cancer, a blood clot etc. you will immediately start to become more aware of information about these things everywhere you go.
For example, about 3 years ago, I started to read more about religion; I started watching debates about religion; I started watching informative videos about religion. I came across various atheists (Richard Dawkins, Christopher Hitchens, Sam Harris). One day I went downstairs to get a drink or something, and on the TV was Richard Dawkins and his TV show talking about religion. A few days after that, an interview with Christopher Hitchens came on the TV. Then, on a panel show called "QI", a question about religion came up. I was thinking to myself "how strange is that?". The reality is, I have seen many shows, many conversations, many questions and many debates about religion; I just never had taken in the information that much to think about it.
Same thing here.
By the way, I get twitching and have almost had twitching everywhere on my body. I had a twitch in my upper left eyelid for about 4-6 months (I can't pin point the exact date it started). I have weird tongue twitches (which actually feel pleasurable). I also have weird facial twitches (again, they sometimes feel pleasurable). I have twitches in my leg muscles and back muscles. Even on my head. As in sometimes above my ear and at the back of my head. My upper arms twitch a lot. Randomly, I sometimes (mainly at night) have body jerks (not the kind where you are just dropping off to sleep then you suddenly jerk).
As I typed this, my bicep twitched and both my calf and thigh muscles twitched, also.
We all have twitching stories to tell.