What is the cause of tightness in the chest and head when reading the Qur'an?

The Quran is a source of healing for the hearts. The distress and harm you feel when reading it may be due to the قرين (jinn companion) from among the devils, who is afflicted by your recitation and tries to divert you from it, or it may be due to possession by another jinn. The treatment is to continue reciting the Quran, maintain the prescribed remembrances (adhkar), make sincere repentance, adhere to prayer, and distance yourself from sins, associating with sinful people, listening to music, and looking at forbidden things. You may also consult ruqyah practitioners, psychologists, and medical professionals.