This will sound so silly but you should take your dog to the vet because it could mean many things like Thyroid issues ETC. It happened to one of my friends dogs who needed medication but once the dogs body asjust to it she was fine.

There are lots of reasons a dog can suffer this. I have had many dogs with separation issues and just general behavioral problems. I have one of the most... needy... breeds out there and I love them... Pomeranians. This is a breed that can actually die if left alone for a day even if with someone, their humans being gone can make them that sick. My shepherd also has anxiety issues. She is blind so being at home all alone is absolutely terrifying for her and she gets very sick and upset. The pom and her together are just fine being home completely alone for 8+hours. So as the previous said, there are lots of things medically that can cause it.

What you have to understand is that to a dog you are its parent. More specifically it's alpha. So when you say it is like a 2 year old, well it is. You have a few ways to deal with it, firstly make sure it is nothing medical. Secondly you need to work with the dog. What I mean by work with it is Train it. You need to socialize it and make sure it has world experience, it deals with other dogs and so on. You need to train it to follow commands, for this you can watch tutorials or get a professional, but it needs to be trained to listen. Both of my dogs are trained to where I do not need a leash with them at any time and neither will leave my side for any reason unless I tell them to "go play". For the shepherd she was easy, they are dogs that like to please, the pom required a training collar that delivered an electric shock for ignoring me. Poodles are extremely smart dogs and need mental stimulation or else they will develop mental issues. Play ball with them, hid their toys and then get them to seek things out. We have taken a ball and stuck it under a plastic milk crate for a jack russel terrier so it had to work the problem to figure out how to get to the ball. If your little one is still having issues being home alone after you have done these things, then you have a dog with true anxiety issues. Again these can be trained out of it to an extent. It will require work on your end though. The concept is that you want to put the dog somewhere it is comfortable and then leave. You don't have to go anywhere, just leave the house. Stay out of the house for about 30 minutes or so (maybe wash the car) and then come back in. Then after about a week or two, make it an hour. Then 2, then 4, then 8 and so on. The trick is your dog will need to learn you are coming home. Always keep in mind your dogs potty pattern as well. If you are letting them out to potty every 4 hours, you cannot be gone for 8 without an accident. you will need to work to extend that as best you can. Our dogs freak out in the kennels, but they are fine if they can wander the house and get in the bedroom. They feel safe in the pack den (bedroom). Some prefer the kennel as my collie did. The training is a must though if nothing more than to just get her to listen enough to leave you be for a bit and be content on the floor at your feet. The shocks may sound mean, but if you watch dogs in a pack some subordinates respond to a growl, some alpha has to throw them into the dirt and clamp down on their throat. If simple training isn't working and the carrot is not successful, time to use the stick (in this case a collar). Our pom listens when training to not need any voltage anymore. We just have to use the vibrate function and she stops the bad behavior right away.