Can expired medicine (cough&cold powder) cause food poisoning? child had slight cough&cold, gave meds (child reported no bad taste), saw theyd expired. 6hrs later vomiting/diarrhea/99.8* temp. result of bad meds or did illness just progress?

Likely unrelated: Such meds get weaker after expiration date but seldom lead to the symptoms you list.It it did you would see them in the 1st hour after it was given. This is likely illness progression.

Viral likely : Swallowed mucus may trigger vomiting during an upper respiratory infection. Avoid expired products, but a viral cause is more likely. Provide fluids, treat fever and please see your pediatrician. Over the counter cough syrup is not generally effective for young children, and not recommended before school age without consulting your pediatrician.

Unlikely from meds: Vomiting and diarrhea can be from variety of causes. People usually see their doctors if symptoms are bad or if they last more than 1-2 days. When diarrhea first starts happening, a person may benefit by stopping eating and start just drinking small amounts (3-4 ounces) of something like Pedialyte or half-strength Gatorade, each hour for one day. That should decrease the vomiting and diarrhea.