Answered by Shaykh Faraz Rabbani
My wife was performing a voluntary fast, while doing house work could not keep up as she was feeling really weak so she broke the fast. What does she do now?
Walaikum assalam wa rahmatullah,
If one breaks a fast, with or without an excuse, it becomes necessary (wajib) to make it up later, even if it was a recommended fast. [Ibn Abidin/Haskafi, Radd al-Muhtar `ala al-Durr al-Mukhtar]
Wassalam.