I'm wondering could she be chewing on grass during the day?
I had a problem with Daisy on Thursday, she woke me up, we sleep together and could not settle down. I asked her "Do you want to go outside" and she jumped off the bed and went to the door, this was in the middle of the night and I took her out and she immediately ran to the back of the patio and vomited, but I believe it was the food she ate at dinner and she has been fine since then.
I would probably get a second opinion if I was you, it doesn't really sound natural for her to do that.
Miss Daisy, Perry and Jackie