All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
The symptoms that you had mentioned about the patient like neglecting to socialize with people, mental and physical pressures when reading the Qur'aan, getting nervous when being with people or looking at them, sudden loss of memory, and the fact that the people who get near to him or deal with him get nervous as well, and so forth, are more likely to be magic rather than being possessed by Jinn. No matter what the condition is, the cure is in the Book of Allaah. Allaah says (interpretation of meaning): {And We send down from the Qur'aan that which is a healing and a mercy to those who believe (in Islamic Monotheism and act on it).}[17:82].
It is also reported that the Prophet used to make Ruqyah (to read some Qur’aanic verses and prophetic supplication) by reading chapters number: 112, 113, and 114. The Prophet said: "These chapters are the best for seeking refuge in Allaah." [Muslim] A treatment for magic is to read the verses in which magic is mentioned or have someone read over the patient, like the saying of Allaah (interpretation of meaning): {Then when they had cast down, Moosaa (Moses) said: "What you have brought is sorcery, Allaah will surely make it of no effect. Verily, Allaah does not set right the work of Al-Mufsidoon (the evil-doers, corrupts, etc.)}[10:81]. One can also protect himself by the legislated mention of Allaah, like the designated remembrance of the morning and the evening, and by being in a state of ablution all the time. Another method of treatment for the patient is to read or have someone read for him the verses of the Qur'aan on water and oil, like reading the beginning of chapter As-Saaffaat [37] and the Ad-Dukhaan [44].
In addition to this, one can seek refuge in Allaah by saying the following supplications:
"I commend you to the protection of Allaah's perfect words from every devil, vermin and every evil eye.", "I take refuge in Allaah's perfect words from the evil He has created.", "In the Name of Allaah with whose name nothing is harmed on Earth nor in the heavens and He is the Samee' (The All-Hearing), the Al-'Aleem (The All-Knowing)". One should read each of the above supplications three times then blow on the water and olive oil. The patient should drink the water and massage his body with it (or have someone massage him). But the patient should believe that the cure is from Allaah and that the treatment is beneficial only with the Will of Allaah.
This person has to repent to Allaah about the bad relations with his father. It could be that what had happened to him was due to bad relations with his father. The family of the patient has to cut relations with the people who practise magic, as magic is one of the seven destructive great major sins. Indeed it is forbidden to go to magicians as this is considered one of the greatest major sins.
The Prophet said: "A person who goes to a soothsayer or magician or diviner and asks him (about something) and believes his sayings, he has indeed disbelieved in what has been revealed to Muhammad (i.e. the Message of Islam.)." [Al-Bayhaqi and Abu Ya’laa]
Allaah knows best.