Open Medical Profile → Medical History and go to Chronic Conditions. Select Add to Medical History, then Chronic Conditions, and then Continue. Select the type of the condition, as well as severity, status, and onset. When the condition is over, you can also specify end. Add Notes — optional if necessary.
If several display languages are active and you have entered a comment, check the language versions, activate Translations reviewed and select Save. Create different diseases as separate entries. You can make changes to the existing entry later via Edit; you can remove information that is no longer correct with Delete.