Baby moaning all day!

Ruled out constipation (had two poops today), he ate well today but hasn't napped well however my son isn't the greatest napper anyways.

He's been moaning all day since he woke this morning, hold him he moans, put him down to play he moans, try to entertain him he moans, feed him breakfast and lunch he moaned the whole time.

What is up with this? I can't figure out what's wrong and I hate to be honest but it's trying me crazy hearing it all day!

Any other mamas experience this?