This sounds like a severe case of obsessive-compulsive disorder. You must be aware that the Elizabethan collar cannot ever cure this disorder. The trigger causing this disorder is no longer around, but the behavior is already ingrained into the brain.
Disclaimer: I'm not a vet or dog psychologist and don't have the competence to cure OCD in dogs. You should speak to a professional dog trainer (not a puppy trainer, but one training problematic dogs).
First you must treat the raw skin or the itching will trigger more licking over and over again. You can rub the skin with coconut oil or special skin products for dogs to keep the moisture in. Feeding one raw egg every second day helps with the regrowth of skin and fur.
You can try the anti-anxiety wrap on your dog and see if it helps. Here's a very good video about how to wrap your dog and here's a pictured instruction. Depending on the size of your dog you can use a scarf, a bandage or cut a strip from an old bedsheet. The wrap should be slightly elastic and as tight as a comfortable hug. Take note that the front wraps around the chest, not the neck.
Then you must start behavior adjustment training. This is the hard part where you need professional help, preferrably in the form of a professional dog trainer, alternatively invest some money into a well-written book about canine OCD and watch many, many Youtube videos.
You should engage the brain of your dog to distract him from his obsessive licking. If your dog is bored, he is constantly reminded of his obsession. If you distract him, he can slowly start to ignore his obsession. You could do this by:
- Aborting a bag filled with treats.
- Teaching him tricks like sit, stay, roll around
- Scent games. Let him sniff out where his treats are hidden
- Just play his favorite game with him
You should select a distraction suited for your dog. Try different methods and find out what works best. Train him daily to teach him the desired behavior so he can switch to this trained game when he has a licking attack.
You must always encourage the desired behavior (calm, no licking) with positive reinforcement, but you must never punish your dog when he relapses into the compulsive behavior! Punishment causes more anxiety and reinforces the compulsive behavior.