What could be wrong? They look so bad now but they used to look
so healthy. When they come to eat they eat like
they haven’t eaten in days and days.
One has a bloated stomach and is so miserable. Please help
with any advice.
This sounds very troubling. Based on your description, several things could be going on.
First, the puppies might be suffering from adverse reactions to the dewormer. This is rare in general, but there is one exception. Collies are extremely sensitive to an antiparasite medicine called ivermectin. If the puppies are Collies, and if they received ivermectin, they may become quite ill and develop neurological signs including seizures.
Another possibility is that the dewormer that was used was not effective (some over-the-counter deworming medicines are not potent). In this case, heavy worm infestations may be causing weight loss, bloated abdomens and extreme hunger. Unfortunately, the seizures are hard to explain in this scenario.
Next, there is a chance that the puppies are infected with a disease such as distemper virus or corona virus. This occurs in puppies that have not been properly vaccinated.
Finally, the puppies may be suffering from congenital irregularities or hereditary problems such as liver shunts. These types of problems can cause all of the symptoms you describe.
I am afraid that I cannot recommend any home remedies or treatments in this situation. The puppies need to see a vet. A physical exam and tests (stool tests and blood tests) are in order for each puppy.