ALS isn't about cramps or pain or burning or stiffness or feeling weak or feeling weird. The sensory neurons, which send signals from the flesh to the brain, are not involved. Instead, the motor neurons which send signals from the brain and brain stem down to the muscles are the ones that ALS destroys. So you muscles never get the "go" signal to contract, and the muscles just lay limp and useless. This is actual clinical weakness. That is paralysis.
Lots of things cause cramps, twitches, and jerks. Perfectly healthy people get them. You're 17 years old, yes? There is no way you have a serious disease involving brain destruction.
Arska, lots of stuff happens to our bodies, especially as we get older. Most of them are no big deal. We should be concerned about something only when it interferes with life, makes us late to work, hard to breathe, etc. The thing that is interfering with your enjoyment of life is your anxiety.