I often use the SCARED scale. There are both parent and child editions you can use to collect data and score. As for medications, Zoloft (sertraline) can be a good place to start. Begin with 25mg/day and titrate higher by 25mg every 5-10 days to a target dose of at least 150mg/day. You can also give hydroxyzine 25mg every 6-8hrs PRN anxiety.