New Bout of Morning Sickness at 12 Weeks

Lisa • Pregnant with Baby #2!
So from 6 weeks to 8 weeks I had constant, unbearable nausea. However I never threw up and at exactly 9 weeks it turned off, like someone had flipped a switch. Luckily those two weeks of morning sickness coincided exactly with my two weeks of Christmas vacation. (I'm a sixth grade English teacher.) Now, however, I'm 11 weeks 5 days and since Thursday I've thrown up four times in four days. It comes out of nowhere. No nausea, no triggers, no warnings. I've barely made it to the bathroom twenty feet away. And a few of these instances occurred in parking lots. It's driving me crazy! I'm so scared to go into work tomorrow, mortified that I'll throw up in front of thirty 12 year olds. How am I going to make this work? I had ways to combat the nausea, but this is a whole new animal. And isn't twelve weeks when the morning sickness is supposed to abate? Why is mine kicking in again? I have my next appointment on Tuesday. I've had no fever or flu symptoms (already had my flu shot in December) so I'm assuming this is pregnancy related. I know there's no way I'll make it to the bathroom if I need to, not to mention I can't leave my class unsupervised. By the time I'd call the office for an assistant it would be too late. Any thoughts?