She shows the classic symptoms for hyperthyroid. Since she may be on the low scale a T4 test is recommended.
It sounds like something she ate caused a GI upset, hence vomiting and diarrhea.
Could be sunflower oil so feed ONLY tuna packed in water, not oil.
Never add probiotics to food because the taste can prevent eating.
Instead, give her half tsp of plain yogurt every day. It has the same acidophilis as a probiotic and cats like the taste.
Get a few jars of human chicken baby food with no onion powder . Most cats LOVE it and will eat it right up.
You can add a tablespoon of rice cereal or boiled white rice to a jar to cure diarrhea.
For vomiting give one quarter of a ten mg pepcid (famotidine) every 12 hours.
Plus give her the tinned food she likes and will eat.
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