In cats, metoclopramide may cause frenzied behavior or disorientation (although it hasn't done so in my Noddy). There are a number of potential drug interactions with metoclopramide, as well. Is your girl taking any other meds?
The standard dose of metoclopramide is .2-.4 mg/kg 3-4 times daily. For my 15.21 lb (6.9 kg) Noddy, that works out to 1.38-2.76 mg 3-4 times daily. But that's not how I dose him. I only give Noddy 1.25 mg (1/4 of a 5 mg tablet) 2 times daily.
Depending on your girl's current weight and the metoclopramide dose you're giving her, you may be able to cut back her dose substantially and still maintain adequate control over her vomiting, without the negative side effects.