Should I stay at 25mg?

Hello everyone! I started zoloft two weeks ago for my extreme anxiety and insomnia. My doctor instructed me to increase my dose to 50 mg yesterday. I did and didn't feel good at all! Felt very jittery, gave me the runs, couldn't sleep at all at night and felt very, very unpleasant and wired. Today I only took 25mg again and feel better. I don't know what happened, maybe higher doses aren't for me. Has anyone stayed at 25mg and saw benefits long term?