I am sorry that Missy is not feeling well, I know this must be very stressful for your daughter and yourself not knowing what is happening. The symptoms that Missy is showing are consistent with being in pain (shaking, slow walking, tense abdomen, etc.). The main source of the pain could be within the abdomen or back (spinal cord); common causes are: A pinched nerve, pancreatitis, ingestion of a foreign body, etc. Less likely we can also see these symptoms when the patient has a fever (infection).
As you can see from the above list there are many possible diseases that can cause the symptoms that Missy is showing. Unfortunately, we are very limited as to what your daughter can do at home. Treatment for Missy would be dependent on knowing the exact cause. For example, if this is related to a pinched nerve she will need prescription anti-inflammatory and pain medication. My other concern is her gums being pale, this could be a sign of anemia, blood shifting to other organs, poor circulation, etc.
I know you were probably hoping to find a solution to Missy's problem on this site. But, based on Missy's symptoms, unfortunately, there is nothing I can recommend that is going to have a significant therapeutic benefit. I would strongly recommend having her checked today by the nearest veterinarian for a hands-on examination. If cost is a concern look into your local ASPCA or Shelter where they often offer veterinary services at a lower cost. I realize that this answer may not be to your liking, and I regret being the bearer of information that you really don’t want to hear. But it would be unfair to you and unprofessional of me were I to provide you with anything less than truthful and honest information. I hope you understand.
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