@Emily Sorry I'm late posting this I've just read the thread and wish I'd got to it sooner to let you know that anti nausea meds work by constricting the stomach so it doesn't throw stuff up. Being uncomfortable and the drooling after the injection could've been caused by the injection itself. Bit late to tell you that now I know

My previous lab had a similar reaction to an anti nausea injection. He couldn't get comfortable, kept roaming about for a good couple of hours. I contacted the vet about it who told me it would be the injection and put in his notes he'd had a reaction to it. I hope Ella is feeling better. If she ever had to have an anti nausea injection again and has similar behaviour you'll know what it might