If your dog is panting and shaking and clingy, they are severely stressed and anxious. I’m sorry you and your pup are going through this. I completely understand how you feel as I had also been through the same experience with our dog when he was younger.
The ThunderShirt Polo Dog Anxiety Jacket is one of the best products that I have ever used in order to calm my dog down when they are stressed or anxious. The concept is similar to an anxiety blanket for adults, but better.
If you don’t want to use a product, the best thing to stop your dog’s panting and shaking and clingy attitude is to help counter-condition the problem with simple dog training.
These calming treats for dogs have worked wonders for our dog. They contain organic chamomile which acts as a relaxer to reduce stress and anxiety which causes dogs to be panting and shaking and clingy.