Open Question: Was it my mother, exams or my weed that made me depressed?

More than a year ago, my mother was diagnosed with breast cancer. Shes better now, but it may be genetic and widespread throughout the process makes me a lot of stress. Around the same time I was doing GCSE's, itself is not particularly difficult, but about 20 exams in foreign countries with his father, mother and two brothers comprehensive cancer care, which is not good. In addition, I started doing a lot of weed a lot, but not a large number. So, I would like to know what a trigger point, perhaps my feelings, because I felt like dog feces, I would like to blame their own from some of the side.