What Causes Muscle Weakness Along With Difficulty Swallowing?
It is not ALS.
Detailed Answer:
I read your question carefully and I am sorry for the symptoms you are experiencing.
Let me start by calming you regarding the ALS worry which is not your case. I understand that looking at separate symptoms on the internet can yield some scary results, but it is necessary to look at things in connection to each other and to patient and evolution in time characteristics. Muscle and joint pain can be produced by simple flu and muscle twitching is an often encountered phenomena especially in anxious people.
You don't have ALS first of all because your age is not typical for ALS, it usually happens in later years and is very very improbable in teenagers. Apart from that, it is a very insidious disease, doesn't have so many manifestations early, it starts with a subtle deficit which progresses into other manifestations over many months.
If your symptoms of muscle and joint pain persist or have been present for a while, I still think you should see your general practitioner for an evaluation and some routine blood tests to screen for other conditions like rheumatological (connective tissue) diseases or infections.
I remain at your disposal for further questions.