Why does the questioner feel pain in her heart after speaking with her sister about religious matters and before sleeping, an feeling that began with her in 1998 and recurs subtly?

There is no harm in joking and laughing if it is free from lying and disobedience, for the Messenger of Allah, peace and blessings be upon him, said: "Indeed, I joke, but I speak nothing but the truth." However, excessive joking harms its owner and deadens the heart. Umar ibn Abd al-Aziz said: "Beware of joking, for it leads to indecency and breeds resentment." Perhaps what you find in your heart is the effect of excessive laughter and joking. Therefore, you should reduce it and occupy your time with what is beneficial, such as studying the Qur'an, reading beneficial books, engaging in meaningful discussions, and permissible speech.