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.
The illness that you were affected with was predestined by Allaah, and you should be patient with this illness and misfortune. You should be content with all that Allaah predestines and decrees, and know that what Allaah predestines is better for the person in all cases. For more benefit, please refer to Fatwa 83577.
You should also know that you will be rewarded during your illness for the deeds that you used to do when you were in good health. Abu Moosa Al-Ash’ari narrated that the Prophet said, “If a person is sick or traveling, the same reward as for the actions that they used to do when they were resident and in good health will be written for them.” [Al-Bukhari]
It may be that what happened to you was because of disobeying your mother, and it could be due to other reasons. In any case, it is hoped that you will be rewarded greatly for being patient for what happened to you and for your good intention. But it does not appear that what happened to you was due to what happened between you and your mother because you said that she had agreed with what you did.
In any case, you have to be kind and dutiful to your mother as much as you can. We ask Allaah to enable you to do all that which is good.
Allaah knows best.