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.
Allaah, the Exalted, says (what means): {So whoever among you is ill or on a journey [during them] – then an equal number of days [are to be made up].} [Quran 2: 184] The days referred to in the verse are those that are between the two months of Ramadan (the previous one and the coming one). It is not permissible to delay fasting the days that you have missed until the following Ramadan comes without a valid excuse. If you have a valid excuse for the delay, such as being chronically sick, which is your case, then you may delay fasting these days until you recover. If trustworthy doctors tell you that your sickness is incurable and that the person who suffers from it cannot fast, then you are required to provide a meal to one poor person per day of fasting that you have missed. The meal should weigh about 750 gm and should be of a type that is commonly consumed – like rice, for example – in one’s dwelling.
Allaah Knows best.