Sure, I've heard of severe vomiting from pregnancy. But now that I have it, I want to know what is really happening in my body.?

Several things. The cause of excessive nausea and vomiting in pregnancy (hyperemesis) is usually unknown. It becomes worrisome if a woman is losing weight or if she becomes dehydrated. Vitamin b6, ginger, and Folic Acid can sometimes help with symptoms.
Keep hydrated. When someone is nauseated or vomiting, there is subsequently some degree of dehydration, which then creates ketosis, which then makes the nausea worse. Thus, the key to treatment involves rehydration either by oral intake or IV therapy, usually in conjunction with an antiemetic to improve the nausea. Described in greek literature, no one to this day knows what causes nausea during pregnancy.