creeping crud
An unknown or unidentified illness, often a rash. I think you better get that creeping crud checked out by a doctor—it's not looking so good.
crud
1. An interjection or exclamation of displeasure. Aw crud, I forgot my wallet—I guess I better turn around and go back for it.
2. Any substance that one deems foul or disgusting. We need a more powerful cleaner to get rid of this crud in the bathtub.
3. One who is viewed with disdain. That guy's a real crud—don't even talk to him.