Hello and Thank You for contacting JustAnswerI am sorry to hear your baby is having trouble.
I would love to help However I would like so additional information in order to better access the problem.
Does she seem painful anywhere including neck or back
Any chance she ate something she should not have
Any vomiting or diarrhea
Are her gums pink and moist
I may have additional questions
Shivering in a dog is most often a sign of pain. Her unwillingness to jump and inactivity lead me to suspect this is a response to pain.
Pugs often develop problems in the neck or back such as ruptured or compression of the discs. This can develop from something as simple as jumping up or down from a couch however it is not uncommon to have no definitive reason for the problem..
If she is known to eat things she should not this could be related to pain in the abdomen
Problems with the liver or kidneys will also cause abdominal pain.
I would suggest having her seen by your vet as the possibilities are many considering her symptoms. If this is a problem with the neck or back the sooner treatment is started the better the chance for complete recovery.
I hope your girl is ok, please reply back if you have additional questions or concerns