My dog keeps gagging like she trying to cough something up but nothing ever does. We've rubbed her throat & even tried help her when she is gagging but to no avail. And it's not all the time. She will be fine & then she start up. There's no provoking at all. She ate & drank last night. She's 4-5 yrs old. I haven't taken her to a vet yet. Wanted to do some research first. This started 2 days ago. Can anyone help?