What is one of the warning signs in this situation that
Alison might need professional help?
being bored in class
o not wanting to go back to school after summer break
feeling different from your friends
hearing voices

You didn't seem to add who Alison is, but the answers give me enough to say which answer is correct.

Of course, there is a very large difference between feeling down and having a serious problem.

Not wanting to go back to school after summer break is completely natural and makes sense, it is just feeling down.

Feeling different from your friends is an issue that people often say isn't that bad, but it is, though rarely requires medical help.

Hearing voices is something that does require medical/professional help. This has a very high chance of being due to schizophrenia, bipolar disorder, and sometimes things such as lack of sleep, drug use, or extreme hunger. Hearing voices is the answer. These issues are serious mental health issues that will definitely need professional help.