Hello & welcome, I am Dr. B, a licensed veterinarian and I would like to help you with today. I do apologize that your question was not answered before. Different experts come online at various times; I just came online, read about your wee one’s situation, and wanted to help.
Again I do apologize that my colleagues could not aid you sooner, but can you tell me:
Did you wean her onto the new diet or make a quick change?
Do you know what plants she was eating (as some are toxic)?
How often is she vomiting?
Is she keeping any food or water down?
Are her gums pink or pale/white? Moist or sticky?
If you press on her belly,does she have any discomfort, tenderness, or tensing?
Could she have eaten something she should not have (ie bones, toys, rocks, chemicals, etc)?