Dog Heartworm Treatment

Earliest appointment we could get with the Vet was tomorrow morning but I just want to get some opinions on whether or not this is probably round worm so I don’t have to rush him to the Vet Hospital and wait for the appointment tomorrow morning… thanks to all who answer in advance

Does anyone know why he would throw it up? Is it just from eating too fast, or should I de-worm him? (It’s cold winter right now here in Canada so I never expect him to get worms)
ps There are no other symptoms.