If you don't believe neurologists who have examined and tested you, why would you believe people you don't know who've never even seen you? No one--not even the world's leading expert on ALS--can tell you with 100% certainty that you don't have it. Or, for that matter, that you don't have pancreatic cancer or a brain tumor or won't die tomorrow in a car accident. That's just not the way life works.

Hypochondria is a very narcissistic condition. Stop focusing so much on yourself and turn your attention outward to another person or thing. Or just grow up. Sheesh.