The worst thing you can do is try and diagnose yourself. Relax first off, the chances of you having something that serious like ALS at your age is VERY rare and by very I mean out of this world unheard of almost.
Go to the doctor and see what's going on, the sooner the better for you and to put your mind at rest.
You need to see your doctor for a full evaluation. The symptoms you're describing could be serious and the only way to know what is going on, is to see a doctor!
Sandy