warts, pimples
瘊 centers on small skin growths: warts and pimples. Both are raised, often unwanted bumps on the skin.
瘊 combines 疒 (sickness) with 侯, which likely contributes the sound. The character is used for skin ailments like warts and pimples.
The sickness enclosure 疒 wraps around 侯, like a skin condition that makes a nobleman (侯) break out in warts and pimples.
For コウ, imagine a nobleman (侯) with a wart on his nose, and the court doctor says, 'Cough (コウ) once and it might fall off!' The cough sound cues コウ.