My cad just had three medications today, as well as a de-worming injection. Tonight when I got home from work, she threw up a few times and it was clear liquid with whole pieces of food in it. Then she started throwing up white foam, about every hour or sp. Is this a possible side effect of her medicine or something else?

Not three medications, I meant vaccines*

I'm having the same problem with my cat, he has thrown up the same way a few times since he got his shots but now I think he is getting a fever, I will call the vet in the morning and ask their advice and ill message you again if I can help.