Wow, well tickle me pink and color me intrigued! There is a lot to unpack here.
At first, when you primed me with a mental health issue, I thought we were going with binge-eating disorder, then it took a sharp left turn when you mentioned the color of his blood!
Ok, so, first off, obviously, only magic (or sci-fi equivalent) would cause someone’s blood to be blue or purple. The notion that deoxygenated blood is blue is not true. It’s really dark red, nearly black. But, I’m assuming this is a magical thing, so let’s side-step that for right now.
Let’s talk about headaches! That’s actually my specialty! (So I apologize in advance for the long-winded response in advance.) There are over 100 types of primary headaches and not all of them are migraines. There are actually super specific diagnostic criteria for migraines that most people who say they “have a migraine” don’t meet. When we are talking about headaches caused by stress, that is a tension-type headache. It is not associated with any other symptoms specifically, like dizziness or fainting and never causes people to become unconscious. Migraines, on the other hand, are not caused by stress, although stress can trigger or worsen a migraine.
Funny enough, Leo, actually does meet the criteria (kinda) for migraine. I would classify his headache as specifically vestibular migraine. Vestibular migraine is accompanied by an aura (or warning sign of impending headache) of dizziness. Like you describe, the dizziness can actually come without headache, but usually occurs 5-30 minutes before the onset of pain (so what you’d describe happening is a bit fast and puts the pain coming first before the dizziness which is out of order). Feeling unbalanced is not uncommon, and indicates vertigo. People report feeling like they are walking on a boat or on clouds or even marshmallows.
Vision changes are also pretty common auras. Again, this would happen 5-30 minutes before the headache and can persist for the duration of the headache or go away after the pain starts. Leo describes his vision getting “hazy”. You could be more specific here. While visual auras vary, the most common types are tunnel vision (blackening of the peripheries), double vision, visual snow (think TV static), and light spots. I would personally go with double vision or tunnel vision for Leo’s condition, just because it is more closely associated with vestibular migraine than the other two.
Here’s the most important inaccuracy I caught: no primary headaches (neither tension type or migraine) cause lose of consciousness. Not even hitting your head causes lose of consciousness longer than a few seconds and any lose of consciousness for any length of time is a sign of serious concussion or brain damage. I see characters knocked out by a blow to the head (either falling or in a fight) in novels or TV frequently, but this doesn’t happen normally and if it does you won’t be “waking up normal” in a few hours. That’s a one way ticket to the ICU and permanent mental deficits for life.
Good news is, I don’t really think it would disrupt the flow of the novel to just axe this bit. Migraines are plenty freaky and disabling without needing to fall unconscious. Associated symptoms which may make Leo “out for the count” include fatigue, mild confusion, difficulty concentrating, sensitivity to light and noise, difficulty speaking, forgetfulness, allodynia (finding non-painful stimuli painful), nausea, and even vomiting. Just think about being incredibly sick and how you can’t to be around anyone or do anything. Then multiply that feeling by a thousand and that’s what a migraine is like.
Now, the headache pain itself is usually one sided, behind the eye or side of the head, throbbing (like you said), and lasts 4-72 hours. Interestingly enough, migraines are genetic, so if his dizziness is related to this blood thing that might be a cool point for accuracy! However, migraine is not a mental health condition, but a primary neurological disorder, meaning their is no known cause.
So in conclusion, it would not be unreasonable to have Leo feeling irritable, dizzy, room spinning, double vision, sensitive to noise and light for about 5-15 minutes prior to when he starts to feel pain. The pain when gradually worsen over the course of 15-60 minutes and his condition would rapidly decline from there. He would most definitely say he needed to lie down, maybe fall on the way there, pick himself back up with the help of Savannah, and then fall asleep on the coach. If she tries to wake him, he will open his eyes or shake his head, moan and groan saying she is hurting him just by touching him, complain about some nausea and the room spinning, maybe vomit, and proceed to make zero sense if he tries to speak at all. (Like pretend someone is drunk.) Then she goes to get Oliver who maybe has a friend or a relative who gets migraine headaches (super common, very likely) and assures Savannah he will be ok and won’t need to go to the hospital. She can put a cold pack on his forehead or behind the neck for pain relief, turn off the lights, tell her he needs quiet, and maybe try to get him to swallow an ibuprofen or ginger (for nausea). Maybe she even has some Excedrin Migraine or Zofran (really common antinausea med, needs a prescription, but it’s used for so many reasons it’s not unheard of to have some lying around) in her meds cabinet for him to take. He wakes up a few hours later with a lingering headache and without any memory of much after he hit the coach. He wouldn’t rub his eyes though, because that is sure to be very painful due to lingering allodynia. Trust me when I say people who have migraines would never say it can’t get worse, cause anything to “take the edge off” is vital to them.