You searched for: “caco thes scribendi
cacoëthes scribendi, cacoethes scribendi (a Latin expression)
1. An incurable compulsion, desire, or drive, to write: As an author, Karl had a case of cacoethes scribendi or an uncontrollable desire to write regardless of the quality of his compositions.
2. Etymology: the full text is, Tenet insanabile multos scribendi cacoethes.: "The incurable itch for scribbling [or writing] affects many"; as stated by Decimus Junius Juvenalis (Roman satirist), 60-140 A.D.

Actually, Juvenal wrote in his Satires, "An inveterate and incurable itch for writing besets many and grows old in their sick hearts."