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, sallallaahu ‘alayhi wa sallam, is His slave and messenger.
We ask Allaah, the Exalted, to cure you from the illness that you are suffering from. As for your question, since you could find a Muslim qualified doctor, then you should not consult a Christian doctor. Since the Muslim doctor has told you that you could try fasting, then try it, given that you are in good health, as you have just mentioned. Also, the opinion of your Christian doctor concerning breaking the fast should not be considered.
That being said, since you can find a Muslim doctor who is qualified to help you in this regard, then you should consult him. If he tells you that fasting will affect your health, then you may not fast. If he tells you that fasting will not harm you, then you are required to fast.
As for your question whether we can help you figure out more about your disease, we advise you to send your question to the section of consults at Islamweb where you can be answered.
Allaah Knows best.