Distended stomach all day despite only having eaten an apple over 12 hours ago. is it normal for this to continue even when not eating?

Cause?: It would depend on the cause of your bloating and distension. If you have a viral gastroenteritis then it would be normal in the course of that illness to have bloating. If the distension is getting worse, you are developing a fever or pain then it would require evaluation.

Abdominal Distension: Abdominal distension is usually, and especially in your case, due to intestinal gas that may or may not be related to what you ate. Often people with particular food allergies can experience this. In my experience, digestive enzymes (over the counter) can help with people who suffer chronically from this. But the bottom line is that it is not serious unless associated with severe pain.