Are the prayers and fasting of a girl suffering from obsessive-compulsive disorder (OCD) regarding purity, due to doubt about the nature of the discharge coming from her, permissible, bearing in mind that she also doubts her ablution and prayers?

Obsessive-compulsive disorder (OCD) is a serious illness, and it gains a stronger hold on a person the more they repeat acts of worship. Satan plays a significant role in bringing it about, as narrated by Ahmad and Abu Dawud that the Prophet, peace and blessings be upon him, said: "All praise is due to Allah who confined his (Satan's) cunning to whispers." The afflicted person must turn to Allah with sincerity and frequent remembrance of Him. Allah Almighty says: "Is not He who responds to the distressed one when he calls Him, and removes the evil?" And He said: "Verily, in the remembrance of Allah do hearts find rest." Part of its treatment is to ignore it and not pay attention to it. Your prayer and fasting are valid, and neither of them needs to be repeated, nor is a ghusl (ritual bath) required for every prayer; rather, what is obligatory is to disregard the doubts.