Sheikh `Abdel Khaliq Hasan Ash-Shareef, states that: “Firstly: the ruling depends on the counselling of a trustworthy specialist Muslim doctor. He/She may subscribe a medicine that treats such case during the month of Ramadan.
Secondly: In case the symptoms of the illness appear in case of encountering an immense pressure, then, it is advised to avoid reasons of pressures and stress while fasting.
Thirdly: If a Muslim with such case were to practice the etiquettes of fasting, in which Allah Almighty obligates the Muslim if someone curses him, he should say: “I’m fasting” [and restrain himself from falling into a sin]. By doing so [and training yourself on it], this may help you avoid the pressures and stress.
Having clarified the above, I believe that fasting is rather a cure for schizophrenia, not a cause for illness unless a trustworthy Muslim specialist doctor permits you not to fast. In case the doctor decides that the illness is chronic and there is no hope of recovery, then the ruling is that such person has to feed one person [two meals] for each day missed. But in case your illness is not chronic and there is hope of recovery, then you have to make up for the days you missed after your recovery or at times when you are able to fast.
But, in case it is possible to observe fasting while taking medication or avoiding reasons of pressure and stress, then fasting is still obligatory on you.