I would get a crate and echo other advice about things to keep him occupied etc.

I will also add that when I was a kid, our lab puppy did the same thing and chewed huge chunks out of the walls in my parents' utility room. My mum concocted a paste using chilli powder, cayenne pepper and other very hot substances. She painted this on the corners (where Tally's chewing started) and it solved the problem instantly. Have you tried a similar idea, e.g. Bitter Apple spray?

If it is SA - or boredom for that matter - crating may well make the dog chew himself or mess the crate.
What is his routine? How much exercise and training does he get? A Labrador is bred to work and is driven to use his instincts.

Don't bank on the anti-chew sprays working! We've used all sorts, and they might as well have not been there - Murphy has an asbestos mouth (and paws, and stomach)!!

I'd go with crating him and re-directing his chewing onto safe objects....

My boys have Kongs, Tug-a-jugs and deer antlers to keep them occupied when we're at work...

They also have a Leo toy as well: http://www.richandrobin.co.uk/kong-g...o-dog-toy.html which seems to be the current favourite!

Not necessarily safer for him, a behaviourist told me that crating for true SA can often distress the dog further and they can then go on to injure themselves in their panic (or, as mentioned, self-harm by overgrooming, nibbling, pulling fur out, etc. with nothing else to direct their anxiety onto). I think it's worth establishing the cause of the behaviour first, if OP can record the dog with a webcam/similar it may shed more light on the 'why'.
Kiki completely chewed the handle off the babygate in her distress and we have several teethmarks in the patio door handle, I would definately not crate her with her SA still at the level it's at - infact, I personally found that giving a bit more freedom in the house did improve the symptoms, it stopped the destructive behaviour of chewing at exits.

I'd go with more exercise/play/training to tire him out and also have him sleep on a dog bed beside yours at night. Surprisingly, free run of the house often solves the problem along with intensive alone trainiing.

Sadly all this resulted in, for us, was having trashed sofas and nearly smashed windows... my dogs are now 5 and 6 and I still would never, ever give them free run of the house if I wasn't in....

But the OP still hasn`t told us a great deal about her dog so we don`t know what the root cause is.
While crating may well be a solution, it may also make the underlying problem worse.

No more chewing last night. Don't know of it was spray or
The bone he had to chew but no hole extensions. And he ate last night and this morning. This dog confuses me more and more each day!!!

So you can maybe put the chewing down to boredom?

Remember that labs are of a working type breed and need a lot of mental stimulation and exercise to keep them on the right track.

Do you play games with your dog at all?

You may want to get him checked at the vets just to ensure the reason he wasn't eating was due his stomach being full of wall paper/plaster.

You still haven`t told us what his routine is. How much exercise and training does he get? It could be boredom or frustration.
A good book to explain how your dog `thinks` is The Culture Clash by Jean Donaldson.