Take a look at the sentence again:
Sick with the flu, Howard craved a big hot
bowl of his grandmother's chicken soup, but in the refrigerator, Howard
had only a jar of olives and a carton of half-n-half, cream of olive soup,
Howard decided, would only worsen how he felt.
A comma splice or fused sentence occurs when you have two complete sentences incorrectly joined together. Sick with the flu is merely an introductory transition that requires a comma to connect it to the main clause that follows.
Go back to the sentence to try again.