Tom is sick his aunt tries many things to help him feel better why do you think the medicines don't work? What causes Tom's sickness? Is it realistic?

The medicines don't work because it is a mental sickness and Tom feels bad  the medicines can't work on this type of things and the thing causing it was the sadness that he had because he thought that Becky was sick because of him and the sickness is realistic cause it is called depression and Tom was just sad and depressed because of Becky.