Can you take her temperature?
It is a good sign her gums are not pale.
There are many things that could cause these symptoms in a young dog, such as eating something she should not that is causing an intestinal upset or infection, or worse, an intestinal blockage; she could have have a fever from an infection; she could have a virus. Panting can indicate fever, pain, distress, or a lung infection or heart problem. She is telling us that something is wrong, but I would need to examine her to find out what and where the problem is.
If she were mine, I would start with a good physical examination: feel her lymph nodes and palpate her internal organs, listen to her heart and lungs, feel the quality of her pulses, take her temperature, try to find an area of pain. Until we identify where the problem is, it is hard to know the best treatment for her. Until you can get her checked out, I would keep her hydrated by offering broth as well as water.
I see she is not desexed, but at her age that is unlikely causing this problem. We do see intact females get a serious infection of the uterus, called a pyometra, but usually not as young as she is.
Let me know what other questions you have.