OK buddy, listen
The odds of getting ALS is 1/100,000, which translates into a 0.001% chance. Now let's take into account your age (you're only 22). Only 5% of ALS diagnoses are prior to the age of 30 and the further away from 30 you get , the better your odds. That puts your chance of being diagnosed with ALS at the very least, 1/2,000,000, so now we're at a 0.00005% of you being diagnosed with ALS. Then let's couple that to the fact that you're only symptom so far is a little bit of twitching. Now can I sit here and tell you with certainty you don't have ALS or will never get it? Absolutely not, I cannot do that. However, I'm fairly confident you are going to be fine. Relax . . . enjoy life . . . go to your neuro and then accept what he/she says.