If your vet suspects a brain tumor,
essential oils are probably not going to be of much help depending on how large the tumor is and what part of the brain it is located in. If it is malignant and she is already having grand mal cluster seizures, it's kind of doubtful that even medication will help much at this point. If it's a benign tumor, however, and it can be removed, then that would be the way to go and then determine which treatment would be best afterward.