My 3-year-old dog (German Shepherd-Pit Bull mix) starting having hiccup-like spasms tonight. It's only when she's laying down. She's conscious and alert and responsive. But I can tell she's very uncomfortable. She seems to want to stand up and stand still. When she lays down, the spasms make her whole body twitch. I called my local vet and they don't think it's anything to worry about. I don't want to pay hundreds of dollars in emergency vet fees at 1:30AM if it's hiccups or something like that. But she's also not making any sort of sound, which is why I didn't think it was hiccups. Any ideas?

Optional Information:
Type of Animal: Dog
Gender: Female
Age: 3
Name of Dog: Lexi

Already Tried:
She's eating, drinking, and going to the bathroom normally. No other symptoms other than the spasms. Almost like severe hiccups. I have a video on my phone that I can forward.