What is the reason for the trembling and increased heart rate that afflicted me after remembering that a jinn enters an impure person, and does it indicate anything?

What afflicted you might be the result of an organic illness, an outburst of lust, or the whispers of Satan. We advise you to fear Allah, maintain your obligatory prayers, and recite the morning and evening remembrances, as well as those before sleep, especially the Verse of the Throne (Ayat al-Kursi). Stay away from forbidden acts such as masturbation, and occupy yourself with what benefits you. Marriage is a solution for those who are able, otherwise, they should fast. You did well by resorting to prayer and reading the Quran during distress.