This is very often a SEVERE reaction to something. You should get your dog to the vet as soon as possible as without intervention it can result in death (and sometimes VERY quickly) on occasion if that's what is going on. You also may want to try and figure out WHAT your dog could be reacting to so as to limit exposure or to be better prepared next time. Did your pet receive vaccines today? What about getting stung by a bee or bit by something else? I hope everything turns out well for both of you.
I have No idea my dog does that but I don't get it I'm am concerned
Same thing happen to my dog. She rubbed her face on the ground for about 30-40min, laid on her side like she was dying, threw up gobs of thick bright yellow mucus. 24 hrs. Later it was like nothing ever happened. And I have no idea what happened.