This morning my cat came downstairs to greet me after waking, as custom. A few minutes later she started meowing very unhappily. I knew what was coming so I ran to grab some paper towel and put it in front of her on the floor. She threw up a LOT of yellow bile, and a little furball. This happened about two weeks ago, but without the furball. She seems healthy otherwise, she is frisky and happy. I called the vet about it the last time it happened and she said it wasn't a big deal unless she was having other symptoms. She's also been sneezing quite a bit in the past couple of days. I came back from a visit from Cuba earlier this week and her bed was all dusty and furry, so it could be allergies. Her stool is normal, behavior is normal, any ideas of what it could be?