My dog has been throwing up everyday, sometimes every other day for 4 days?

It's like a foamy white. It's been almost everyday for 4 days. Could this be due to the fact that my mom is gone? She is very attached and my mom is on vacation. Is this just stress? She gets a little lethargic after she throws up but then is normal and happy the rest of the day, lethargy lasting only a little while. What should I do? I stopped giving her treats, just in case it was food bothering her....