I take psychiatric medicines and the doctor forbade me to fast. I live in Switzerland and the doctor is Swiss. The medicines gives a lot hunger and thirst. Must I fast Ramadan even I'm sick?

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

At first, you have to look for a Muslim trustworthy doctor, since the opinion of such a doctor only is accepted in this case; i.e., breaking the fast due to sickness. If you do not find that, then you can follow the opinion of the Swiss doctor you mentioned in your question as long as he is an expert doctor.

Then, you have to make up the days you break the fast when you become able to do so. But, if your sickness lasts for a long period (chronic), then you have to feed one poor person for every day that you did not fast with a Mudd (measure equals 750 grams of rice…) of food.

For more benefit on expiation for breaking the fast, please refer to Fataawa 113006, 113207, 113713, 114215, 131133, 216094.

Allah knows best.