All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad is His slave and messenger.
You have to consult a trustworthy doctor who is specialized in this area of sickness. If he tells you that fasting will result in sickness, worsen your condition, or delay your recovery, then you may not fast in Ramadan because you have an excuse and are entitled to take the concession for fast-breaking. Yet, you have to make up for the days that you miss whenever you are able to do so. The type of sickness that allows breaking the fast in Ramadan has been discussed by the four Schools of Jurisprudence.
However, If the doctor tells you that fasting will not affect your health, then you must fast the entire month of Ramadan and are not allowed to break the fast as long as you are able to bear it.
Allaah Knows best.