Yikes!!
Some doctors won't prescribe combined hormone birth control to women who get migraines with visual auras (seeing spots) because it increases your risk for blood clots and stroke. Plus, for some women, estrogen (going on or off of it) causes an increase in migraines. If this is the case, you really shouldn't be on it. I'd see the doctor- things like seeing spots are scary and you need to make sure there's nothing going on. You could also still have a migraine from going off of it, just a low-grade one. That would explain your headache and vomiting and diarrhea.
Talk to your doctor about it. Like I said, some doctors think it's an issue and some don't. My docs won't let me on estrogen because of my migraines and the risk of stroke. (Not that I think you had a stroke) But it's something you should be aware of.
There are other options like mini pills, the shot, iud's, or (I think) implanon. But definitely talk to your doc.