Good Afternoon and welcome! I am Dr. Loretta, a licensed veterinarian and I am happy to answer your question.
The vaccine can certainly cause a digestive disturbance disturbance as a reaction especially since your girl is so young and tiny. It also may be that she got into something that did not agree with her. If this were contagious, your other one would also have this. It is good, for now, to separate them and treat your girl this way:
Fast your girl for 12-24 hrs to allow the digestive tract to calm down and heal.
Give her Pepcid AC or Famotidine at 0.5 mg per pound every 8 hrs. That can be purchased over the counter at the pharmacy.
Give only small amounts of water during the fast or ice cubes
After the fast, feed rice and boiled chicken (2/1)
If the vomiting and diarrhea have resolved, then wean her back onto regular food. If the this persists especially during the fast, take your gal to your vet for an exam and lab work to determine the cause for this. This is extremely important since this can cause dehydration or other more serious concerns such as an infection or intestinal obstruction.
Does that make sense to you?
Please let me know if you have ANY other questions. My goal is to give you 100% satisfaction and if you are not yet satisfied, please REPLY so I can clarify for you.
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