Sir, my son, who is 25 years old now was good in all respect and spheres. However, for the last 13 years, he has changed a lot. In every respect, be it in studies, in behaviour towards others has gone worst. 13 years back Shani dasha has started and Shani is in Aries. So we have made every possible efforts as per the guidance of astrologers. But, no good results have been seen yet. SO, I am apprehending some one has made black magic on him. kindly suggest me what to do.