Sickly

[Sarah]

In [persistent]ly poor health, [infirm], sick all of the time.

By extension, looking sick or unhealthy.

[Britney]

When someone looks way too [thin] to be [healthy]
Someone who is normally good looking but looks [peculiarly] bad either because they are ill or from lack of trying to look presentable

[Gregory]

[so sick] that [not even] the word [sick] can describe something so sick

[Becky]

Often ill; in poor health.