Need some advice my puppy is sick?

I got my bf a mini dachshund for xmas. He has been doing great until today. He is 10 weeks old and is current on shots and everything. Today he stopped eating and began throwing up a white mucus stuff. I will call the vet tomorrow but does anyone have any idea what it could be? He has had his parvo shots. My 3 year old grandson was over last night and I think he might of fed him part of an orange popsicle but other than that he has had nothing but purina one. I didn't figure the popsicle would hurt him to much. Any ideas?