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, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
If a person is not able to perform Hajj due to old age or a chronic disease that is unlikely to be cured, and he has the financial ability to afford Hajj, then it is incumbent on him to authorize someone else to perform Hajj on his behalf.
The Maaliki scholars maintained that as long as he is not able to perform Hajj, it is not incumbent on him to perform it, and it is not valid, according to them, for someone to perform Hajj on behalf of another.
As for the case of the questioner, he apparently is not of this kind, for he is sound at most times and enjoys his mental faculties. Hence, he is not allowed to authorize someone else to perform Hajj on his behalf, for he is likely to get cured. However, if it is feared that he may suffer fits of epilepsy during the Hajj or might get troubled because of the crowdedness, then he may delay Hajj until Allaah Almighty cures him. He is not required to perform Hajj on an immediate basis, according to the view that suggests that Hajj is obligatory on an immediate basis. In Ash-Sharh Al-Mumti‘, commenting on the author's words, "If he is unable due to old age or a disease that is not likely to get cured, then he is required to authorize someone to perform Hajj and ‘Umrah on behalf of him," Shaykh Muhammad ibn Salih Al-‘Uthaymeen said:
It is understood from the author's words that if the disease is likely to be cured, then he is not required to authorize someone to perform Hajj on behalf of him and he is not required to perform Hajj by himself, given his inability. Moreover, he may defer the performance of Hajj as, due to his disability, he is not subject to the obligation of performing it on an immediate basis.
Allaah Knows best.