Recurring thoughts please help!

For a little under a month now. I’ve been thinking about death. And it’s making me really anxious. Like I’m a healthy 17 year old girl with no health problems so far. But every night I go to sleep thinking “what if I don’t wake up” I get so scared and during the day the same thoughts come into my mind. I don’t want them. They make me so anxious that I cry a lot now. I’m actually so happy to go to my yearly physical soon to make sure I’m healthy. Any suggestions on how to clear my mind?