Depression. My pg entrance. kindly help.

Hi.. I hv finished my mbbs.. preparing for PG entrance. Gave my first attempt last year and couldn't get a good rank. So I'm studying again for the next attempt. I hv family issues, my father is a patient of Ca and my mother is schizophrenic. My brothers marriage came up last year so I couldn't concentrate on studies. I looked after family issues. When results came I became depressed. I was a very bright student in my school and college. I took some time n started preparing again. But I'm having difficulty to study, as everyone is expecting me to take responsibility and I  want some time to study. I have relationship issues also. I have insomnia, Crying spells, and decreased appetite. I feel very stressed. I have become dull and don't like to mingle with ppl. I dnt feel like sharing these with my family as already so many problems at home. I dnt want to burden them. I want to get out of this cycle of depression and study for my PG entrance. kindly help.