Five years ago, I had Hepatitis during the month of Ramadan and was advised to break my fasting. The problem is that I do not remember the exact number of missed fasting days. However, I estimate that I fasted seven days and I made up for the missed fasting days based on this estimation. My question is: Is it permissible for me to fast some extra days, due to my doubt, because I fear that I might have forgotten some days?
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.
Whoever forgot the number of days that he had missed in Ramadan should fast until he predominantly thinks that he has made up for all the missed fasting days.
Hence, if you believe that you have most likely made up for all the missed fasting days, you will not be required to fast any more days.
However, if you still have doubts as to whether you have not made up for all the missed fasting days, then you will have to fast until you believe that you have certainly or most likely made up for all the missed fasting days.
Some scholars, however, are of the opinion that one is not required to make up for the missed fasting days that one has doubts about whether or not he is required to make up for them because, in principle, one is free from their liability.
Shaykh Ibn ‘Uthaymeen said, “If one is in doubt as to whether he missed three or four fasting days, then he has to make up for the least number because that is certain while the other number is doubtful. Indeed, in principle, one is free from liability from them, but it is more prudent to make up for the doubtful days. If he makes up for these days and they really were obligatory, then he has certainly freed himself from liability; otherwise, this will count as a voluntary fast and Allah The Almighty never wastes the reward of those who do good deeds.”
The case in question is a very simple one and there is no harm if you made up for the doubtful days to clear your liability if they were obligatory, otherwise they will count as voluntary fasting days.
Allah Knows best.