All perfect praise be to Allah, The Lord of the Worlds. I testify that none is worthy of worship except Allah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and messenger.
When someone does something during the daytime of Ramadan that necessitates observing an expiation, then he is required to do two things:
First: To make up for the day on which the fast was invalidated.
Second: To observe the required expiation, which is freeing a slave, and if it is not available, one has to fast two consecutive months. This is according to the Hadeeth narrated on the authority of Abu Hurayrah . [Al-Bukhari and Muslim]
Interrupting the sequence of the fast by failing to fast for even one day without a Sharee'ah-approved excuse necessitates starting the whole fasting all over again. But if there is a Sharee'ah-approved excuse, such as sickness, madness, fainting, etc, then the past fasting is valid and its consecutiveness is not interrupted. Thus, one has to fast the remaining days only. If one is unable to fast, as when it causes him unbearable hardship, then he has to feed sixty needy persons.