It’s probably Giardia. Which is what you mentioned in your post. Super common, parasitic in nature, treatable by prescription. Simple stool sample with you go will determine that and you’re good to go. But you have to treat it with rx. Even if your symptoms subside or disappear the parasite is still living inside you.
Hello! I actually think GERD is right on the money. It does really often smell like sulfur and if bad enough will make you throw up. Now, violent throwing up? If you eat a fair amount of meat and eggs, that has been associated with this sulfur smell as well when throwing up or burping. My understanding is that H Pylori is associated with gastric ulcers. Have you taken any heartburn medicine and does it help you? How often do you vomit?