Is it obligatory to make up the prayers for the day the questioner fell ill 11 years ago, knowing that she prayed some of them and left others due to severe pain?

A sick person who retains his mental faculties is not permitted to abandon prayer. If he abandons it, he must make it up. The missed prayers from the three aforementioned days must be made up. As for the day on which some prayers were offered and others were missed, and they cannot be distinguished, it is obligatory to make up all five prayers.