Can stress cause morning sickness?

I've been in school (college) since I found out I was pregnant in August. I've also had morning sickness since August which is annoying since I am 22w. But I've been off for a week now for Christmas break, and all of a sudden I feel great. I've been stressing out like crazy with school, doctor's visits, trying to figure out insurance since I had none, work, and just being sick all semester, but this last week, not having homework and tests to worry about has made a huge difference. I haven't thrown up, my mood is better, and I feel like I have so much more energy even though I'm working longer and more grueling hours.

Has anyone else felt this way? Has stress caused you to feel physically ill? I'm actually heavily considering taking my next semester off just to make myself feel better during these last couple months of pregnancy. It's a hard choice because I love school but I really feel like I need to take a few months to really take care of myself and focus on keeping healthy for baby.

Any thoughts or comments are super welcome because this is a huge decision and I feel like I'm stressing myself out just trying to decide what to do.