This has not happened in a while, but the first day of my period, I wake up early then start to vomit. This goes on until about 2pm [very weird]. I try to sleep it off which works most of the time, but it has been getting worse. since it is the morning I wake up hungry, meaning no food in my stomach, so i throw up stomach acid for hours. I;m not sure if its rly stomach acid, its yellow/light/dark, and last time it was blood as well. I am feeling better know but I will really like to know what is going on.