Is psychic disease related to bad karma?

I suffer from a psychic disease (borderline disease of personality) which has turned my life into hell for at least half of the time, I spend several hours a day crying desperately and nothing helps, not the psychotherapy nor the medicines. I am obsessed with the idea that I'm suffering so much because in some way I "deserve" it according to the karma law, for having done something very bad in a past life. Is it true? It may seem weird, but this answer means a lot to me. Thank you for your answers in advance.