One should never be satisfied with the explanations official（see yesterday’s article on 病). While searching in various books, I found an interesting comment on this character, which allows us to better understand its logic.
The right part 丙 no longer only has the phonetic function but makes sense. Indeed, the first representation evoked a kitchen stove; underneath, we make the fire, above we put a saucepan: 丙
This is why this part was found in characters related to the cooking of food. Its spelling sometimes was like that of 内, nèi, character.
To differentiate them, the character has been slightly modified and it is this new form that has come to us: 丙. Besides the idea of the man lying on the bed seen yesterday with the right part 疒, 丙 no longer has only a phonetic function but brings the notion of warmth and, therefore, fever and consequently, illness.
13 July 2020