Is repeating an oath by Allah to end obsessive-compulsive disorder (OCD) regarding purity, and the subsequent breaking of the oath and fasting, considered a "vain oath" (laghw al-ayman)?

You are not liable for the oaths you have taken or broken due to obsessive thoughts, because you are considered to have been coerced. However, for any oath you have taken or broken without the influence of obsessive thoughts, you are required to offer expiation for each oath. This expiation consists of feeding ten poor people, or clothing them, or freeing a slave. If you are unable to do any of these, then you must fast for three days.