Blood in my cat's vomit

[Cor]

My almost 10 year old cat, Judy, was just outside, and I could hear her vomitting. When I looked outside, I saw her vomit, and there was blood in the vomit. what is this caused by? I did recently change her brand of cat food, but integrated it to her gradually. Please help me.
Thank you, Corinne

[SSAC]

Could indicate a foreign body ingestion. Take her to the vet for an x-ray
ASAP
If she is any outdoor cat I'd also be concerned that she could have gotten into anything toxic.