All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
First of all, we ask Allah to cure you and cure all the sick Muslims.
If you left those Sunan (plural of Sunnah) because of illness while you were continually observing them and were it not for the disease, you would have performed them, then we hope that Allah will record their reward for you.
It is confirmed in the Sharee’ah that the excused person gets the reward of the acts of obedience that he was keen on performing and which he fails to perform due to a legitimate excuse.
Al-Bukhaari reported that the Prophet said: “When a slave falls ill or travels, he gets a reward similar to that which he gets for the good deeds he usually performs when at home [not travelling] and in good health."
Ibn Hajar said in Fat-h Al-Baari: “This applies to the one who is used to performing acts of obedience, but he was prevented from it, while his intention was to do it had he not been prevented.” [End of quote]
For more benefit, please refer to Fataawa 368947 and 115973.
Allah knows best.