It is permissible for an ill person who cannot fast Ramadan, to refrain from fasting. If possible, such a person is to make up the missed fast days after Ramadan. If the illness is chronic, it is obligatory to pay a fidya [compensation] which consists of feeding a poor person for each missed fast-day. This is based on the hadith of Ibn Umar (may God be pleased with them both) who narrated that the Prophet (peace and blessings be upon him) said: “Whoever dies with unperformed fast-days of Ramadan, then [the responsible family member] is to feed a poor person on his behalf for each missed fast-day” [recorded by Al-Tirmidhi and Ibn Majah].

In your case, it is permissible to refrain from fasting. And if your illness is chronic, you must feed a poor person for each day you do not fast the equivalent of 2. 75 kg of rice.

God the Almighty knows best