I need help. I feel overly stressed and it won’t stop.

For the past few weeks, I’ve been feeling extremely stressed to the point it’s gotten physical. I wake up in the middle of the night, my back is starting to hurt, the heart monitor on my Fitbit is always marked as high (once it alerted abnormal heart rate, but I’m not sure what that means.) My anxiety is through the roof. I cannot relax. And all of this has gotten so overwhelming that I’ve completely lost all my motivation. I can’t muster up any willpower to do homework, clean my room, or go running, no matter how hard I try. I can’t even leave my bed or my room sometimes. The worst part is, I’m not even sure why this is happening. I used to have after school activities that got me out of the house and this stress started around the time those ended, but idk if that’s the cause because we also started state testing and my friends stopped hanging out with me as much around the time it started too. I’m so incredibly tired of this. I feel like crying out of frustration. Even when I’m laying around and doing nothing, I feel on edge. I can’t sleep at night. I don’t know what to do. I’m only 14. This shouldn’t be happening. Please, if you have any idea what’s going on or how to solve this, I would really appreciate it. I can’t do this anymore.