I may not be a vet, but I do think that if a dog can't even relax at home, long-term anxiety medication really should be on the table. Dogs take a long while to flush stress hormones from their body, and if they're constantly stressed... well, that's hard on a dog physically and mentally, and often means that the dog can't take training on-board.
Assuming he's been cleared for pain, thyroid issues, tick-bourne illnesses, etc. you really need a vet that will take this seriously and work with you. Get a referral to a veterinary behaviorist if you have to. I think you mentioned you work for this vet? So I understand that it may be a big benefit to go there if you get any kind of employee discount, but if they're not helping your dog...
As far as training goes, the only major advice I have at this point is to avoid picking him up as much as possible. Many small dogs actually find this uncomfortable and scary, and of course it removes all control he has of the situation. Try to find other solutions to move him when you have to - nose targeting, stairs/ramps/steps of some kind for getting up places he needs to go, wearing a short house line in case you need to physically encourage him to move, etc.
In the meantime you can work on counterconditioning being handled and picked up and try to make it a happy experience by working him up slowly - and again, only actually lifting him when it's absolutely unavoidable. He may benefit from some cooperative care training, which gives a dog more control over being handled by teaching them (and the handler!) how they can consent to various physical manipulations - lots of great YouTube videos on this! But again, depending on his stress level he may struggle to take this kind of training on board without medical assistance.
Assuming he's been cleared for pain, thyroid issues, tick-bourne illnesses, etc. you really need a vet that will take this seriously and work with you. Get a referral to a veterinary behaviorist if you have to. I think you mentioned you work for this vet? So I understand that it may be a big benefit to go there if you get any kind of employee discount, but if they're not helping your dog...
As far as training goes, the only major advice I have at this point is to avoid picking him up as much as possible. Many small dogs actually find this uncomfortable and scary, and of course it removes all control he has of the situation. Try to find other solutions to move him when you have to - nose targeting, stairs/ramps/steps of some kind for getting up places he needs to go, wearing a short house line in case you need to physically encourage him to move, etc.
In the meantime you can work on counterconditioning being handled and picked up and try to make it a happy experience by working him up slowly - and again, only actually lifting him when it's absolutely unavoidable. He may benefit from some cooperative care training, which gives a dog more control over being handled by teaching them (and the handler!) how they can consent to various physical manipulations - lots of great YouTube videos on this! But again, depending on his stress level he may struggle to take this kind of training on board without medical assistance.