Best of luck tracking this down; definitely don't let a forum posting be a replacement for seeing a doctor if it's a real concern!
You started your post saying you felt crappy at after day 1 - do you stabilize after the fateful Night One? I sometimes get to feeling poorly at altitude, too, but after day 1 my health always stabilizes. I've never vomited but I get nausea due to intense headaches during the first night or when I wake up the next day. Happens at any significant mountain altitude (I live 50' above sea level), even 7,000' as you describe. After that first night/morning, I'm right as rain for the rest of the trip, regardless of duration or further altitude gain.
I'm still dialing in a 100% solution, but for me the improvements I've made are absolutely tied to hydration (have enough, sometimes crazy amounts) and nutrition (magnesium, potassium, electrolytes, esp. if drinking a ton) - a banana and salty snacks on day 1 are good, only going to electrolyte replacements help if it's really hot. Car-camping and day-hiking at altitude the day before sometimes helps, sometimes not. I never exceed 2mph on the first day. When the headaches come - the only gateway symptom - caffeine is the drug that always helps me. Excedrin Migraine and coffee in the morning, in conjunction with the right food and water, have always nipped it in the bud for me.
None of this may work for you. My symptoms sound easier to control and my nausea is always triggered by headaches, and I can usually manage to eat something. But just offering some food for thought to see if you can draw any parallels or get some new ideas.
Best of luck, man.