Level 3 problems are the easiest to identify and handle in that there are specific procedures for helping students in crisis. Basically, you need to stay calm and know who to call for help. See How to make a referral.
In dealing with a student who exhibits Level 1 or Level 2 behavior you may choose to approach the student or the student may seek your help with a problem.
Convey support and understanding by summarizing what you hear the student saying by including both content and feelings (“It sounds as if the experience of moving away from home was a big change and now you’re feeling lonely and isolated”).