Sorry you're having a rough time.
It's very common for anxious people to be anxious about taking a medication. That alone could be causing your anxious reaction at night. It's kind of like a self fulfilling prophecy, you know? You worry about something enough, and it ends UP causing your anxiety.
Are you in therapy? If not, you need to start ASAP. That's truly the BEST way to address anxiety. Medications will help by decreasing the symptoms, but therapy is where you will learn coping techniques, and how to change your thought process. A therapist would be the one to really work with you on getting past that anxiety about the medication.
It's far too soon to assess how the Zoloft will work for you. Also, remember that most of the time, the medications make us feel a little worse before we feel better. It's tough to wait it out, but it's necessary. The best thing you could do is to try to keep yourself as busy and distracted as possible, especially at night, when you've been having the anxiety. The more you're thinking about it, the more anxious you will feel.
Hang in there....update us on how you're doing!
I am not any any medication at all and get anxiety. I get palpitations like you describe, and know it is due to that. If you think the pill may be causing this problem, do you want to stop taking it? We all have memory problems, not unusual, even in one as young as you. It is a problem wondering whether to take pills or not. Are we better on them or without them. Wish I knew the answer to that. It is a personal thing. I have done both, and trying to cope without medication.
Hope you get over this episode, and so sorry you are experiencing problems.