Tracy,
you poor thing and your poor lab. :( You didn't say how old he was... is he around 9months -2 years old?? Just curious.
You might consider having him work up the time again to build his confidence. Is there anyway you can put him in his pen, then work around him for 10 minutes? Ignore his yelps/whinings and tell him "no-quiet", but just keep working in the garden or nearby. Then at 10 minutes or when he becomes settled, just open the door and walk away. Don't say anything to him and don't let him get "happy" by jumping up on you. Make it a non-event.
Then just keep pushing up the time again.... If he's quiet for 30 minutes of you being within sight of the pen... Leave for 10 minutes or so, then come back and work around the pen for another 10. When he relaxes, open the door, and walk away.
Just don't praise/comfort him for his loud behavior no matter how badly you feel. Then you reinforce that there is something out of the ordinary to worry about in his brain. :rolleyes:
Hope this might help you out. Good luck with you both :)
toodles